Liver Diseases And Hepatic Encephalopathy
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Liver Diseases And Hepatic Encephalopathy

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  • 1. LIVER DISEASES AND HEPATIC ENCEPHALOPATHY Scientific Product Monograph Merz Pharmaceuticals GmbH Frankfurt am Main
  • 2. LIVER DISEASES AND HEPATIC ENCEPHALOPATHY Scientific Product Monograph Merz Pharmaceuticals GmbH Frankfurt am Main
  • 3. CONTENTS Product profile 6 6 Clinical results with Hepa-Merz® 72 6.1 Clinical research with Hepa-Merz® 74 1 Liver function and hepatic encephalopathy 9 6.2 Experimental clinical studies with Hepa-Merz® 75 1.1 Ammonia metabolism and detoxification function of the liver 9 6.2.1 Effects of Hepa-Merz® on ammonia concentration 75 1.2 Liver diseases as the cause of hepatic encephalopathy 13 6.2.2 Effects of Hepa-Merz® on protein synthesis in muscle 82 6.2.3 Effects of Hepa-Merz® on neurometabolites 84 2 Hepatic encephalopathy – clinical picture and pathogenesis 23 6.3 Clinical results with intravenous Hepa-Merz® therapy 86 2.1 Definition and clinical forms of hepatic encephalopathy 23 6.3.1 Hepa-Merz® infusion in comparison with placebo 86 2.2 Precipitating factors in hepatic encephalopathy 27 6.3.2 Meta-analysis of placebo-controlled trials 93 2.3 Pathogenesis of hepatic encephalopathy 30 6.4 Clinical results with oral Hepa-Merz® therapy 96 2.3.1 Neuropathological changes 30 6.4.1 Hepa-Merz® Granules in comparison with placebo 96 2.3.2 Ammonia and the glial hypothesis 32 6.4.2 Hepa-Merz® Granules in the medical practice 100 2.3.3 Additional pathological mechanisms 35 6.4.3 Hepa-Merz® Granules in comparison with lactulose 105 6.5 Summary of results with Hepa-Merz® 106 3 Diagnosis of hepatic encephalopathy 40 3.1 Diagnostic procedures 40 7 Safety and tolerability 108 3.2 Early diagnosis 42 3.3 Criteria for assessing degree of severity 8 Chemistry, toxicology and pharmacokinetics of Hepa-Merz® 110 and monitoring the course of disease 45 8.1 Chemico-physical data 110 8.2 Toxicology 111 4 Treatment of hepatic encephalopathy 51 8.3 Pharmacokinetics 111 4.1 General therapeutic concepts 51 4.2 Dietary therapy 52 9 Basic information 112 4.3 Drug therapy 53 10 Abbreviations 117 5 Mechanism of action and pharmacodynamics of Hepa-Merz® 59 11 References 119 5.1 Mechanism of action 59 5.2 Pharmacodynamic effects in animal experiments 62 5.2.1 Effects of Hepa-Merz® on ammonia metabolism 62 5.2.2 Effects of Hepa-Merz® on metabolism in the brain 64 4 5
  • 4. PRODUCT PROFILE Hepatic The clinical picture of hepatic encephalopathy (HE) ari- mechanisms contribute to the neurotoxins present in encephalopathy ses as a complication of chronic and, more rarely, acute portal vein blood reaching the brain via the systemic cir- liver disease. It is a potentially reversible functional culation. Once there, neurotoxic ammonia in particular disorder of the brain with neurological and psychiatric disrupts the function of neurones and astrocytes, giving symptoms which may occur with different degrees of rise to the symptoms of hepatic encephalopathy. An severity (HE grades 0-4) and in varying combinations. important aim of treatment is therefore the reduction of Deficits of psychomotor function can be demonstrated the ammonia present in the body by lowering the in the early stages; even at the start, these represent a amount of ammonia produced and increasing its detox- certain risk especially at work and in traffic. At first there ification. are mild non-specific disturbances of sleep, drive, mood and cognitive function. As the condition prog- The active ingredient of Hepa-Merz® infusion concen- L-ornithine- resses, symptoms of psychomotor retardation and neuro- trate, granules and chewable tablets is L-ornithine- L-aspartate muscular disturbances (e.g. asterixis) occur as well as L-aspartate, the salt of the natural amino acids ornithine lowers neurotoxic NH3 disorientation and memory defects. With higher grades and aspartate. Through the mechanism of substrate of HE, the clinical picture is characterised by increas- activation, the two substances stimulate the urea cycle ingly altered levels of consciousness (hepatic coma). (which metabolises ammonia to urea) in the liver and The early diagnosis of hepatic encephalopathy is of glutamine synthesis in the liver, muscle and brain. Urea great importance for the future course of the condition and glutamine (after further metabolism) can be excret- and is possible with e.g. psychometric tests that are ed via the kidneys. L-ornithine-L-aspartate thus activa- easy to perform. tes the two important metabolic pathways in the human body for the detoxification of ammonia. Functional impairment The most common cause of hepatic encephalopathy is of the liver cirrhosis of the liver. Hepatic encephalopathy occurs in L-ornithine-L-aspartate has been used for many years L-ornithine- up to 70% of patients with cirrhosis at some time during for the treatment of conditions associated with impaired L-aspartate the course of their disease. These patients in particular hepatic detoxification (e.g. in cirrhosis of the liver) and is effective should be carefully monitored for signs of hepatic en- its sequelae, when there are symptoms of minimal (sub- and well-tolerated cephalopathy. Increasing structural replacement with con- clinical) and overt hepatic encephalopathy. Hepa-Merz® nective tissue leads to the loss of functioning hepatic is usually well tolerated or very well tolerated. parenchymal tissue and a reduction in the detoxification capacity of the liver. In addition, developing portal In the most recent clinical trials, the efficacy of Hepa- L-ornithine- hypertension leads to the formation of a collateral circu- Merz® infusion concentrate and granules was tested L-aspartate lation through which non-detoxified blood can by-pass against placebo. L-ornithine-L-aspartate showed a sta- evidence-based the liver to reach the systemic circulation. Both these tistically significant effect with respect to an improve- medicine 6 7
  • 5. 1 LIVER FUNCTION AND HEPATIC ENCEPHALOPATHY ment in mental state (reduction in the HE grade), in- Hepatic encephalopathy is a complication of both chronic creased detoxification (reduction of the ammonia con- and acute liver diseases. The most common underlying centration in the blood) and positive effects on psycho- cause is the reduced detoxification capacity of the motor function (reduction of time required in the number damaged liver in combination with a collateral porto- connection test). With these findings, evidence-based systemic circulation through which ammonia-containing medicine criteria for demonstrating efficacy have been blood by-passes the liver to reach the systemic circula- fulfilled. tion. 1.1 Ammonia metabolism and detoxifi- Summary: cation function of the liver The efficacy of Hepa-Merz® infusion concentrate and granules in the treatment of minimal (subclinical) and overt hepatic encephalopathy in An important function of the liver as a metabolic organ Ammonia production liver disease associated with impaired hepatic detoxification (e.g. in is the detoxification of ammonia produced from nitro- in the intestine, cirrhosis of the liver) has been clearly demonstrated in placebo-control- gen-containing compounds. In the hepatic cells ammo- muscle and kidneys led clinical trials. Treatment with L-ornithine-L-aspartate lowers the nia is converted to urea and glutamine which can be ammonia concentration and thus improves the mental state and psycho- excreted via the kidneys. motor performance. Hepa-Merz® is well or very well tolerated in the The ammonia present in the blood is released endoge- majority of cases. nously during cell metabolism from nitrogen-containing compounds such as proteins, amino acids, nucleic acids and amines, or synthesised by the intestinal flora and absorbed into the blood stream. A large quantity of ammonia originates in the intestines. Mention should be made of both bacterial ammonia production in the large intestine and abacterial degrading of nitrogen-contain- ing metabolites in the small intestine. Ammonia synthesis in the muscles and kidneys contrib- utes to the ammonia concentration in the blood to a smaller extent. Ammonia produced in the muscle in- creases in proportion to the work of the muscle; in resting muscle, ammonia uptake and excretion are approximately in equilibrium. In the kidneys, only a small quantity of ammonia is produced under normal conditions. 8 9
  • 6. An increase in ammonia synthesis is seen in special type of (reversible) detoxification also takes place in the circumstances e.g. on treatment with diuretics and in brain and the liver. hypokalaemia. Glutamine is broken down in the kidneys by the action In the liver itself, large quantities of ammonia are also of glutaminase to give glutamate and ammonia; gluta- produced during protein breakdown. This is immediate- mate is further converted to a-ketoglutarate by the ly detoxified, however, so that the liver does not contrib- release of a second ammonia molecule. The ammonia ute to the blood ammonia concentration when its function released in the kidneys can be excreted in the urine; a is intact. small quantity is re-absorbed. Ammonia Ammonia is physically dissolved in the blood and is in metabolism equilibrium with ammonium ions (NH3/NH4+); this is pH- Urea in the body dependent. With a rise in the pH (alkalosis), the propor- tion of diffusible toxic ammonia (NH3) increases. Under physiological conditions there is a natural equi- Small intestine Large intestine librium between ammonia production and ammonia detoxification. The normal non-toxic serum levels in the peripheral blood are in the region of 30 µmol/l. The highest ammonia concentrations are found in the portal vein blood, which carries the ammonia produced in the intestinal tract. Muscle Liver Figure 1.1 summarises the pathways involved in the Glutamine metabolism of ammonia in the human body. The liver is the most important organ to detoxify am- monia produced in the large and small intestine, Urea muscles and kidneys. Most of the urea produced there is excreted via the kidneys, with a small proportion Kidney being excreted via the gastrointestinal tract. Urea Some of the ammonia present in the human body is detoxified in the muscles. Glutamine is produced from Fig 1.1: Ammonia metabolism in the body ammonia and glutamate. Apart from muscle tissue, this 10 11
  • 7. Ammonia Some 70-80% of the ammonia present in the portal These highly specialized cells, also referred to as scav- detoxification vein blood is removed during passage through the liver. enger cells, form only 5-10% of the liver parenchymal in the liver This is due to the synthesis of urea and glutamine. cells. Urea synthesis and glutamine synthesis take place in Summary: two different cell systems organized sequentially in the A large proportion of the ammonia present in the blood comes from the hepatic acinus (Figure 1.2). gastrointestinal tract, with contributions in the internal milieu from mus- cles and kidneys. Ammonia-containing blood is transported through the portal vein to the liver where it is detoxified by the formation of urea and glutamine. Functional units of periportal and perivenous hepatocytes in Periportal hepatocytes Perivenous hepatocytes the acini of the liver control the ammonia concentration in the blood. Cytosol Cytosol Mitochondrion Mitochondrion Glutaminase 1.2 Liver diseases as the cause of hepatic encephalopathy Carbamyl phosphate Glutamine synthetase Glutamine synthetase I The most common liver disease that causes hepatic encephalopathy is cirrhosis of the liver. This can also Glutamine arise as the result of other liver diseases (e.g. hepatitis, Urea fatty liver). Genetic enzyme deficiencies and acute liver failure are much less common causes of hepatic en- Glutamine Glutamine cephalopathy. Urea Hepatic encephalopathy is a relatively frequent complica- Hepatic encephalopa- Figure 1.2: Detoxification of ammonia in the liver. Formation of urea and glutamine in periportal and tion of cirrhosis of the liver, particularly if there is a collat- thy is a common com- perivenous hepatocytes (after Häussinger, 1990) NH4+: Ammonia; Cbm-P: Carbamyl phosphate; Orn: eral portosystemic circulation. Hepatic encephalopathy plication of cirrhosis Ornithine; Cit: Citrulline; Arg-Suc: Arginine succinate; Arg: Arginine can be demonstrated in 30-70% of these patients. The of the liver pathology of cirrhosis of the liver consists of destruction of In periportal hepatocytes, ammonia is converted to urea the normal parenchymal structure and replacement of the in the urea cycle. In the subsequently activated perive- parenchyma with nodular connective tissue. This is a nous hepatocytes, the ammonia is metabolised to glu- common chronic liver disease with a prevalence of about tamine by the action of glutamine synthetase. 1%. 12 13
  • 8. Cirrhosis: The cause of cirrhotic changes in the liver in more than Haemodynamic consequences of cirrhosis causes and half of the patients is chronic alcohol intoxication. In a of the liver degree of severity third, cirrhosis is the result of hepatitis. More rarely there is a metabolic cause (e.g. Wilson’s disease, haemo- The connective tissue changes with resultant loss of Portal hypertension chromatosis, alpha-1-antitrypsin deficiency etc.) vital hepatic parenchyma increase the vascular resis- and toxic NH3- or vascular cause (e.g. chronic right ventricular failure) tance of the liver leading to the development of portal concentration in or an unexplained disease process. Progression of hypertension. Raised pressure in the portal vein induces the brain cirrhosis is more or less the same whatever the aetiology. the formation of a collateral circulation between the por- The degree of severity of cirrhosis is usually expressed tal system and other veins, known as a portosystemic by the Child-Pugh classification, stages A, B and C, shunt. Portal vein blood by-passes the liver through which takes into account the laboratory parameters of oesophageal and abdominal varices, rectal varices, bilirubin, albumin and the prothrombin time as well as abdominal wall vessels and intrahepatic collaterals to ascites and encephalopathy (Table 1.1). hepatic veins. This means that portal vein blood which is particularly rich in ammonia (due to absorption of the ammonia produced in the gastrointestinal tract) flows directly into the systemic circulation, by-passing the liver through these collateral vessels. Because of the resultant hyperammonaemia, muscles and the brain take up greater amounts of ammonia to compensate; this gives rise to toxic ammonia concentrations in the Parameter Number of Points 1 2 3 brain. Encephalopathy Grade 0 Grade I/II Grade III/IV Reduced ammonia detoxification in the liver Ascites none slight severe Bilirubin (mg/dl) ≤2 2–3 >3 At the same time, the loss of functioning hepatic tissue Bilirubin (µmol/l) (≤34) (34–51) (>51) has an effect on the detoxification capacity of the liver. Albumin (g/dl) >3,5 2,8–3,5 <2,8 Ammonia can no longer be broken down in sufficient Prothrombin time (seconds above standard) 1–3 4–6 >6 quantities. Urea synthesis and glutamine synthesis are or INR <1,7 1,8–2,3 >2,3 reduced in patients with cirrhosis. In contrast, there is Table 1.1: Assessment of hepatic function reserve based on Child-Turcotte criteria, modified by Pugh. increased activity of glutaminase, which converts gluta- Addition of the points gives the Child-Pugh stage: A (5-6 points), B (7-9) and C (10-15) mine into ammonia, i.e. release of ammonia is greatly increased in the cirrhotic liver (Figure 1.3). 14 15
  • 9. % synthesis rate/wet liver weight Percentage ± SEM Normal state Haemodynamic causes Metabolic causes µmol/hxg Control 500 Fatty liver ** Cirrhosis 400 300 Urea Urea Urea Glutamine Glutamine Glutamine 200 NH + 4 NH + 4 NH + 4 100 ** ** * ** 0 Urea synthesis Glutamine synthesis Glutaminase activity *p<0,01 **p<0.0005 vs control Figure 1.3: Activity of urea synthesis, glutamine synthesis and glu- Figure 1.4: Pathophysiology of hepatic encephalopathy in cirrhosis taminase in biopsies of histologically-confirmed normal liver tissue, of the liver (after Gerok, 1995) fatty liver tissue and cirrhotic liver tissue. The data are based on the calculation of synthesis rate per wet liver weight (µmol/h x g). The Data on the incidence of subclinical hepatic encephalop- synthesis rate of control liver tissue corresponds to 100% (after Gerok, 1996) athy vary, ranging from 30% to 80% (Häussinger and Maier, 1996). Early stages in particular often remain Figure 1.4 gives an overview of the factors playing a role unrecognized. in portosystemic encephalopathy – pathological hae- modynamics and reduced detoxification in the liver. Fatty liver (steatosis) is the most widespread liver dis- Fatty liver and Both mechanisms contribute to the increased ammonia ease in the population. It may be the result of various cirrhosis in the blood and the occurrence of hepatic encephalop- conditions (e.g. diabetes mellitus, disorders of lipid athy. metabolism) or toxic effects (alcohol, drugs, industrial toxins). The most common cause is toxic damage due The clinical course of cirrhosis of the liver is generally to alcohol misuse. chronic and progressive. The most important complica- tions are bleeding from oesophageal or abdominal var- An increased deposit of triglycerides in the hepatic cells ices, ascites, jaundice, clotting disorders, renal failure is characteristic of fatty liver. Firstly small deposits can and hepatic encephalopathy. On average, about 40% be seen (fine droplet fatty change). As the condition of patients with cirrhosis develop overt hepatic en- progresses, the size of the fat droplets in the hepatic cephalopathy during the course of the disease. cells increases (large droplet steatosis). 16 17
  • 10. The fatty deposits lead to an overall enlargement of the Non-alcoholic steatohepatitis (NASH) also belongs in Non-alcoholic liver. the group of non-alcoholic fatty changes in the liver, steatohepatitis (NASH) with a spectrum ranging from steatosis through steato- Symptoms of a fatty liver include sensations of pressure hepatitis and steatofibrosis up to cirrhosis. and fullness in the right side of the upper abdomen and frequently also pain in the region of the liver, as well as Inflammation of the liver may have various underlying Hepatitis and cirrhosis flatulence, fullness, nausea and reduced performance. causes. The most important of these are hepatitis vi- of the liver The enlarged liver is usually easily palpable through the ruses, autoimmune processes and drugs. On occasion abdominal wall. Results of liver-specific laboratory tests the cause may not be identified. Chronic hepatitis may may occasionally be abnormal, depending on the extent develop into cirrhosis of the liver and hence be an indi- of liver damage and loss of function. rect cause of hepatic encephalopathy. With fatty liver the detoxification function may already be Viral hepatitis is the most common. Table 1.2 gives an limited. Studies have shown that urea and glutamine up-to-date overview of hepatotropic viruses (Caspary synthesis are reduced in fatty livers (see Figure 1.3). 2001). As a rule, acute viral hepatitis heals without caus- Values lie somewhere between those in cirrhotic tissues ing cirrhosis. Hepatic encephalopathy may occur in and those found in healthy livers. It is therefore probable fulminant viral hepatitis even without cirrhosis. In chron- that minimal hepatic encephalopathy is also present in ic hepatitis, cirrhotic changes in the liver arise as part of patients with fatty livers, or can develop under the the inflammatory process. Chronic viral hepatitis can influence of additional precipitating factors (see section therefore be an indirect cause of hepatic encephalop- 2.2). athy. Hepatitis B, for example, becomes chronic in some 10% of cases and a number of these patients go At first these processes are reversible with the removal on to develop cirrhosis. In contrast, hepatitis C follows of the cause, i.e. in most cases misuse of alcohol. With a chronic course in some 80% of cases and often continued presence of the toxin, the process frequently develops into cirrhosis of the liver. progresses with increasing fibrosis developing into cir- rhosis of the liver. The effects of alcohol may also give rise to inflammation of the liver with hepatic cell necrosis and cell infiltration – alcoholic hepatitis – which may also develop into cirrhosis of the liver. 18 19
  • 11. HAV HEV HBV HDV HCV Normal CAH IIa CAH IIb CAH cirrhosis Picorna- Calici- Hepadna- Delta- Flavi- n=50 n=44 n=41 n=37 Virus family viridae viridae viridae viridae viridae 160 * Genome RNA RNA DNA RNA RNA * Incubation time (days) 14–45 14–60 30–180 30–180 14–180 Ammonia (µg/dl) 120 * Transmission faecal-oral faecal-oral parenteral parenteral parenteral Diagnositics (acute infection) anti-HAV anti-HEV HbsAg anti-HDV anti-HCV 80 IgM IgM anti-HBc-IgM IgM HCV-RNA Becomes chronic no no <5 % <10 % 50–80 % 40 (adult) (co-infection) arterial 90 % <80 % venous 0 (perennial) (super-infection) Cirrhosis of the liver – – 20–30 % 30–40 % 20–30 % Figure 1.5: Arterial and venous plasma ammonia concentrations in with chronic hepatitis different stages of chronic active hepatitis (mean ± standard devia- Oncogenicity no no yes ? yes tion). The statistical significance * (p<0.05) refers to the comparison with normal controls (after Müting et al., 1988). Notifiable disease* I, D I, D I, D I, D I, D CAH: chronic active hepatitis Table 1.2: Characteristics of hepatotropic viruses (after Caspary 2001); I = illness; D = death; *Obligation to notify disease in accordance with §3 of the Federal Infectious Diseases Protection Law Fulminant viral hepatitis in particular but also drug-induc- Acute liver failure ed toxic reactions may rarely lead to acute liver failure which has a dramatic clinical picture. This is defined by In less common autoimmune hepatitis, loss of immunologi- the combination of severe liver insufficiency and alter- cal tolerance leads to self-destruction of the liver. The ation in the level of consciousness with hepatic en- etiology and mechanisms are mostly unclear. The cephalopathy. The diminution in liver function is character- inflammatory process leads to loss of functioning paren- ized by a rapid fall in clotting factors, with a sharp rise chyma and to fibrotic changes in the liver. in transaminases and accompanying jaundice. The appearance of hepatic encephalopathy is an unfavour- In chronic hepatitis, the reduced detoxification capacity of able prognostic sign. Various classifications of the the damaged liver tissue appears even before cirrhosis degree of severity of acute liver failure have been de- develops. A study on patients with chronic hepatitis showed fined based on the interval between the appearance of that even before the formation of a by-pass circulation – jaundice and encephalopathy. In general it can be said associated with progressive liver damage – there is an in- that the more quickly hepatic encephalopathy follows crease in the blood ammonia concentration (Figure 1.5). the signs of jaundice, the worse the prognosis, i.e. 1 week 20 21
  • 12. 2 HEPATIC ENCEPHALOPATHY – CLINICAL PICTURE AND PATHOGENESIS in hyperacute forms and more than 4 weeks in sub- 2.1 Definition and clinical forms of acute. hepatic encephalopathy The symptoms of encephalopathy in acute liver failure Hepatic encephalopathy (HE) is a metabolically induc- Definition of hepatic do not basically differ from hepatic encephalopathy due ed, potentially reversible, functional disturbance of the encephalopathy to other causes. However, there is a risk of cerebral brain which may occur during the course of chronic and oedema and fatal cerebral herniation as a result of acute liver diseases (see section 1.2). The term encom- raised intracranial pressure. The prognosis in acute liver passes a syndrome of individual neurological and failure is poor; mortality without a liver transplant is psychological components that may occur in different about 80%. combinations and with varying degrees of severity. The symptoms and signs of hepatic encephalopathy do not basically differ from encephalopathies of other genesis; the definition therefore includes a concurrently demon- strable liver disease. Occasionally, portosystemic encephalopathy (PSE) is Summary: classified as a subgroup of hepatic encephalopathy. The most common liver disease which causes hepatic encephalopathy This refers to encephalopathy in cirrhosis of the liver in is cirrhosis of the liver. The typical picture of disease includes liver cell combination with portosystemic collateral circulations damage with reduced detoxification capacity in combination with colla- (see section 1.2). However, this form cannot basically teral portosystemic circulations. Other liver conditions may develop into be distinguished from other forms of hepatic encepha- cirrhosis during the course of the disease e.g. fatty liver or hepatitis. In lopathy. acute liver failure, hepatic encephalopathy may occur without cirrhosis or portosystemic shunts. The clinical picture of hepatic encephalopathy is very Clinical picture and variable and can be associated with impairment of intel- degree of severity lectual and psychomotor functions as well as changes in personality and level of consciousness. Clinical pro- gression varies greatly: acute, episodic, fluctuating and chronic forms are possible. Hepatic encephalopathy is divided into five degrees of severity according to the West Haven criteria, on the basis of clinical symptoms and signs as well as the findings of psychometric tests (Table 2.1). These 22 23
  • 13. divisions are based largely on the mental state of the Minimal (subclinical) encephalopathy is present in 30- patient; they range from HE grade 0 with no distur- 70% of people with cirrhosis. The burden of this distur- bance of consciousness to deep coma with HE grade bance depends on the demands made on the individu- IV. al. Diminished performance may be of particular importance in manual work (e.g. operating conveyer belt) and driving a car. Reduction in the quality of life HE grade State of conciousness/ Behaviour Neuromuscular and personal safety may be associated even with HE intellect symptoms grade 0 (see section 3.2). Minimal clinically normal but clinically normal but disturbance of fine Typical symptoms and signs of HE grades I-IV are pre- Overt hepatic subclinical abnormal pathological abnormal pathological motor function and psychometric tests and psychometric tests sented in Table 2.1. The degree of severity of hepatic encephalopathy I reduced concentration and personality changes disturbance of fine encephalopathy can progress very quickly. prolonged reaction time, motor function Neuropsychiatric symptoms of overt hepatic encepha- sleep disorders, fatigue (reduced alertness) lopathy are extremely variable. The first clinical indica- II retardation, lethargy marked personality asterixis, slurred tions are, for example, sleep disturbances, loss of drive changes, temporal speech and mood swings as well as loss of fine motor func- disorientation tions. Poor attention span, lack of concentration and III disorientation, somnolence, bizarre behaviour, hypo- and hyperreflexia, stupor delusions asterixis, convulsions reduced mental agility can be taken as signs of dimin- IV coma ceased areflexia, loss of tone ished cognitive function. As these are non-specific, they are often not recognized as signs of hepatic encepha- Tab. 2.1: Degrees of severity of hepatic encephalopathy: Classification of the mental state according lopathy. With HE grade II, symptoms of psychomotor to West Haven criteria (modified after Conn and Bircher 1994) retardation with disorientation and memory defects appear. Characteristic flapping tremor (asterixis) is a sign of neuromuscular disorder, as are ataxia, dysarthria Minimal hepatic In the stage of minimal (subclinical or latent) hepatic and increased reflexes. Occasionally, hallucinations and encephalopathy encephalopathy – HE grade 0 – the patient has no delusions occur. complaints and on direct questioning has no symptoms Changes in personality – often the intensification of a belonging to grade I. Sleep, concentration, fine motor previously existing characteristic – may be pronounced. functions, general performance and mood are not In the later stages of hepatic encephalopathy, alter- affected. Even so, results of psychometric and neuro- ations in the level of consciousness determine the psychological tests show subtle abnormalities, provid- clinical picture. HE grade IV is characterised by deep ing evidence of cerebral disturbance in the sense of coma with response only to painful stimuli. retardation of psychomotor functions. 24 25
  • 14. Hepatic Hepatic encephalopathy may also occur in acute liver 2.2 Precipitating factors in encephalopathy in failure, e.g. with fulminating hepatitis (see section 1.2). hepatic encephalopathy acute liver failure This is basically indistinguishable from the symptoms seen with chronic liver disease; however, the distur- A great variety of factors can precipitate or exacerbate Many precipitating bances of cerebral function appear more abruptly and hepatic encephalopathy (Figure 2.1). Often there is factors progress more rapidly. States of delirium, restlessness interplay of several factors. The severity of the cirrhosis and seizure tendency are more common than with and the extent of collateral circulation do not necessar- other forms of hepatic encephalopathy. ily determine the likelihood of encephalopathy. Hepatic encephalopathy may be induced by a certain combina- tion of precipitating factors even in patients without recognizable impairment of liver function and no mark- ed portosystemic shunt volume. Summary: The definition of hepatic encephalopathy encompasses the liver disease Increased ammonia in the brain Volume deficiency and the cerebral dysfunction. Assessment of the severity of the condition • Increased ammonia production: • Diuretics is made clinically on the basis of the mental state (HE grade in accordance Protein-rich diet (in forced mobilization of ascites) with West Haven criteria). With the minimal or subclinical form (HE grade GI bleeding • Vomiting 0) there are no obvious clinical deficiencies but the results of psychomet- Hypokalaemia • Diarrhoea ric tests are abnormal. Increasing deterioration of the level of conscious- Constipation • Bleeding ness becomes apparent with HE grades I-IV, reaching deep coma by HE Infection grade IV. • Increased passage of ammonia Drugs into the brain: Metabolic alkalosis Transjugular intrahepatic porto- (esp. diuretics) systemic stent shunt (TIPS) Vomiting Hypoxia Figure 2.1: Precipitating factors in hepatic encephalopathy (after Caspary 2001) The majority of precipitating factors is associated with increased nitrogen or an increased number of nitro- genous metabolites in the blood. 26 27
  • 15. The common precipitating factors of azotaemia, bleed- Hepatic encephalopathy may also be precipitated TIPS and hepatic ing from shunt varices, infections and protein-rich diet, following the creation of a transjugular intrahepatic encephalopathy lead to increased nitrogenous compounds that are bro- portosystemic shunt (TIPS) as a therapeutic measure. ken down to ammonia which cannot be sufficiently Encephalopathy becomes overt in about a quarter of detoxified because of impaired liver function. At the TIPS patients. The main indications for a TIPS are same time there is decompensation of ammonia detox- haemodynamic problems, especially prophylaxis of ification. recurrent bleeding from oesophageal or abdominal Hypovolaemia, aspiration of ascites, diuresis, hypoka- varices. If there is not already severe hepatic encephalop- laemia or hyponatraemia may lead to disturbances of athy (grade II-IV), the risk of encephalopathy has to be fluid balance, acid-base balance and electrolyte con- accepted, since these haemodynamic complications are centrations. As a result, more ammonia may be produc- difficult to treat and potentially fatal. Elderly patients ed in the kidneys, hepatic and renal blood flow be (>60 years of age) are particularly at risk. The patho- reduced and detoxification in the liver impaired. Di- physiological changes responsible for the manifestation uretics also directly inhibit urea synthesis in the liver. of hepatic encephalopathy in patients with shunts are Metabolic acidosis also adversely affects urea synthe- described in section 1.2. sis. Other factors that commonly precipitate overt hepatic encephalopathy are sedatives and tranquillisers, espe- cially benzodiazepines. These substances have a neu- rodepressant action and in this way may promote hepat- ic encephalopathy. Since these drugs are metabolized in the liver, impaired hepatic function prolongs their half- Summary: lives; this means that a relative overdose may occur All conditions that increase the ammonia concentration in the blood – by even when normal dosages are taken. Sedative drugs increasing ammonia production or disrupting detoxification – are pos- should therefore be prescribed for patients with cirrho- sible precipitating factors in the manifestation of hepatic encephalopa- sis only in special circumstances. thy. Neurodepressant agents (e.g. benzodiazepines, alcohol) may like- wise precipitate hepatic encephalopathy. When a TIPS is created as a Alcohol induces hepatic encephalopathy not only by therapeutic measure, the risk of hepatic encephalopathy must also be causing cirrhosis of the liver; it may also act as a precip- accepted. Elderly patients (>60 years of age) are particularly at risk. itating factor through its neurodepressant effects. 28 29
  • 16. 2.3 Pathogenesis of hepatic chromatin. These pathological changes indicate a key encephalopathy role for the astrocytes in the pathogenesis of enceph- alopathy (Figure 2.2). Explanation of the pathogenesis of hepatic encepha- lopathy requires investigation of the relationship be- tween liver function and cerebral function, two highly complex systems. Results are frequently not easy to interpret and give rise to further questions. The many symptoms and signs and their variability with respect to the degree of severity and progression make it dif- ficult to find a common pathomechanism that explains all the forms of encephalopathy. Despite intensive scientific research, it has not yet been possible to completely elucidate the pathophys- iological mechanisms of hepatic encephalopathy. However, it is certain that increased ammonia con- centration in the blood contributes to the pathogene- sis. There is probably synergy with other pathome- chanisms. Figure 2.2: Alzheimer type II astrocytes Alz: Alzheimer astrocyte, N: normal astrocyte 2.3.1 Neuropathological changes Swelling of Hepatic encephalopathy is basically a reversible dis- astrocytes turbance of cerebral function. Damage to neuronal The astrocytes are important components of the blood- cells is not seen. In neuropathological studies, how- brain barrier. The uptake of substances from the blood ever, changes can be identified in the morphology of into the brain requires the transastrocyte transport the astrocytes. In acute liver failure, the astrocytes are mechanism. Astrocytes are in close contact with neuro- swollen. In cirrhosis of the liver, neuropathological nal cells and are involved in the metabolic processes of changes can be seen, which are described as Alzhei- neurotransmitters and regulation of ion concentrations mer type II astrocytosis. These astrocytes are charac- in the brain. terized by large swollen nuclei and margination of the 30 31
  • 17. 2.3.2 Ammonia and the glial The mechanism of neurotoxicity of ammonia in the brain Neurotoxicity hypothesis has not yet been completely explained. There is experi- of ammonia mental evidence of disturbances of the cerebral energy Pathogenetic An increased ammonia concentration in the blood cer- metabolism and neurotransmission, direct modulation significance tainly contributes to the manifestation of hepatic en- of neuronal activity and an indirect effect on the neu- of ammonia cephalopathy. There is no pathogenetic concept in rones via the astrocytes. On the basis of recent studies, which ammonia does not play a key role. The following functional disturbance of the astroglia with resulting points in particular support this: dysfunction of the neuronal cells is possibly the most important neurotoxic mechanism of action of ammonia. • In most patients with hepatic encephalopathy, the ammonia concentration in the blood is raised. Accumulation of glutamine (a product of ammonia Ammonia and Only 10% of patients have normal levels. detoxification) in the cells is the main cause of the astro- glial swelling • In cases of hyperammonaemia, lowering the cyte swelling. Only these cells contain glutamine syn- ammonia concentration leads to improvement in thetase, an enzyme capable of detoxifying ammonia in the symptoms. the brain (Figure 2.3). • Hepatic encephalopathy occurs far and away most commonly in patients with cirrhosis of the liver and portosystemic collateral circulations, in whom insufficiently detoxified blood – especially with respect to ammonia – reaches the brain. NORMAL HYPERAMMONAEMIA • There is a certain correlation between ammonia concentration and the severity of the hepatic SYNAPSE ASTROCYTE SYNAPSE ASTROCYTE encephalopathy. Gln Gln • Conditions where the ammonia is raised can pre- Gln Gln NH3 Gln NH3 Gln cipitate or exacerbate hepatic encephalopathy, while a fall in ammonia concentration improves Glu NH3 NH3 Glu NH3 NH3 Glu Glu the clinical symptoms and signs. Glu Glu In animal experiments hyperammonaemia induces GLU-RECEPTOR GLU-RECEPTOR changes that are also seen in liver patients (e.g. cerebral oedema and raised intracranial pressure) as well as Figure 2.3: Diagrammatic representation of glutamate-glutamine cycle in the glutamatergic synapse numerous neurochemical changes similar to those and the influence of hyperammonaemia found in humans. (Gln = glutamine; Glu =glutamate; (1) = glutaminase; (2) = glutamine synthetase) 32 33
  • 18. Other substances such as cytokines and benzodiaze- may arise. There may be changes in the permeability of pines or conditions such as hyponatraemia may be the blood-brain barrier with symptoms of raised intra- synergistic to the ammonia effects and thus contribute cranial pressure. In addition, effects on the activity of ion to the astrocyte swelling, or may even be the main channels, disturbances of neurotransmitter and recep- cause of this change. tor functions, and damage to the neuronal energy sup- ply are to be expected. The glutamatergic neurotrans- Figure 2.4 gives an overview of the different factors mitter system that controls cognitive function is contributing to the pathogenesis of hepatic encepha- probably involved in the process; due to the increased lopathy. consumption of glutamate needed to detoxify ammo- nia, glutamate deficiency results in the glutamatergic neurones. Frequently it cannot be determined how Changes in post- Changes in Changes in the much the functional changes in neuronal activity are synaptic receptors neurotransmitters blood-brain barrier due to direct toxic effects of ammonia and how much to indirect effects of the glial swelling. Swelling and functional disturbance of the astroglia 2.3.3 Additional pathological Neurotoxin ammonia/amino acid imbalance mechanisms Impaired liver function Besides the role of ammonia and the concept of glial swelling, there are indications that additional patho- mechanisms exist. These may be synergistic or may Figure 2.4: Interplay of various pathogenetic factors in hepatic encephalopathy even determine the manifestation of hepatic encepha- In acute liver failure, glial swelling occurs with clinically lopathy. overt cerebral oedema. Findings from recent studies have shown that there is also a disturbance of cell vol- There is evidence for considering the neurotoxic effects Other endogenous ume homeostasis with glial swelling in chronic liver dis- of other endogenous substances – for example, mer- neurotoxins eases and hepatic encephalopathy (Häussinger et al, captans which are formed during the breakdown of 2000). sulphur-containing amino acids (e.g. methionine) by bacteria. These substances are responsible for the Many potential functional disturbances of the glial cells characteristic foetor hepaticus. They inhibit Na+/K+ themselves and of the glial-neuronal communications ATPase and potentiate the neurotoxicity of ammonia. 34 35
  • 19. Phenols are also neurotoxins; they lead to coma in ani- that the concentrations of aromatic amino acids in the Neurotoxicity mal experiments. They are derivatives of the amino brain also increase while the branched-chain amino of ammonia acids phenyl alanine and tyrosine, and are formed in the acid concentrations are reduced (Figure 2.5). gastrointestinal tract. Short and medium chain fatty acids are produced by the physiological intestinal flora during the break- NH3 down of fatty acids, and can also be formed in the liver itself. They inhibit Na+/K+ ATPase and urea synthesis in the liver. In addition, there is some evidence that these compounds increase the tryptophan uptake into the brain and thus affect transmitter metabolism. Glutamate Glutamine Glutamate Glutamine Increased The blood-brain barrier is a complex physiological permeability of the functional unit which protects the brain from metabolic blood-brain barrier disturbances in the rest of the body. In acute liver Glutamine Glutamine failure, the permeability of the blood-brain barrier is increased in a non-specific manner. Certain changes in Figure 2.5: Diagrammatic representation of ammonia and amino acids exchange. Ammonia taken up into the brain is converted to glutamine, which is exchanged for the branched-chain amino acids the blood-brain barrier are also seen in chronic liver fail- (BCAA) and aromatic amino acids (AAA) present in the plasma, which use the same transport system. ure. The transport capacity for neutral amino acids is In the case of portosystemic encephalopathy, increased levels of ammonia in the blood lead to raised concentrations of glutamine in the brain. The higher AAA to BCAA concentration ratio in the blood increased but reduced for basic amino acids, ketone promotes the entry of AAAs into the brain through exchange with glutamine (after Conn, 1994) bodies and glucose. At the same time, the ammonia- dependent rise in intracerebral glutamine formation increases the uptake of neutral amino acids into the brain. The selective changes in permeability that can be The aromatic amino acids are substrates for neuro- observed are possibly related to the glial swelling. transmitter synthesis – tyrosine and phenyl alanine for dopamine, and tryptophan for serotonin. The excess Amino acid imbalance In chronic liver disease, the blood shows a typical supply of substrates may mean that substances such and “false neurotrans- amino acid distribution profile. The quantitative rela- as tyramine, octopamine and phenyl ethanola- mitters” tionship between aromatic (tyrosine, phenyl alanine, mine are formed via secondary metabolic pathways. tryptophan) and branched-chain amino acids (valine, These act as “false neurotransmitters” by competing leucine, isoleucine) shifts towards the aromatic amino with the normal transmitters for the same receptors and acids. On the basis of this observation, it is assumed thereby disrupting neuronal activity. 36 37
  • 20. GABA-ergic On the basis of the therapeutic neurodepressant effects transmission of benzodiazepines, which are notable precipitating fac- Summary: tors for hepatic encephalopathy, the hypothesis has Every last detail of the pathogenesis of hepatic encephalopathy has not been proposed that so-called endogenous benzodiaze- yet been fully elucidated. Ammonia certainly plays a key role. The asso- pines and related substances (endozepines) which can ciated glial hypothesis, which assumes an underlying mechanism of dis- be found in the blood and brain as well as in plant prep- rupted interaction between the altered astrocytes and other cellular ele- arations and foodstuffs, contribute to the pathogenesis ments of the brain, brings the various findings together in a of hepatic encephalopathy by their agonistic actions on comprehensive manner. The concept of synergistic mechanisms be- the GABA receptors. Gamma-aminobutyric acid tween the observed influencing factors is plausible and correlates with (GABA) is an important inhibitory neurotransmitter in the the variable symptoms and signs to be seen in hepatic encephalopathy. brain and GABA receptors are to be found on neurones and astrocytes. Activation of the GABA-ergic system has a neurodepressant effect. Serotonin, The increased uptake of tryptophan into the brain leads noradrenaline to an increased formation of serotonin. The density of serotonin receptors decreases while their affinity increases. Changes regarding the neurotransmitter noradrenaline are also seen in hepatic encephalopathy, which may possibly have pathogenetic significance. Zinc, manganese Results of recent studies have suggested an associa- tion between hepatic encephalopathy and the trace elements zinc and manganese. It has been shown that the activity of enzymes in the urea cycle is reduced when there is zinc deficiency. NMR studies in patients with hepatic encephalopathy have indicated deposits of manganese in the basal ganglia. The question of how relevant these findings are to pathogenesis remains open. 38 39
  • 21. 3 DIAGNOSIS OF HEPATIC ENCEPHALOPATHY 3.1 Diagnostic procedures In alcoholics with cirrhosis of the liver, Wernicke-Korsakov Differential diagnosis syndrome and delirium tremens from alcohol withdraw- Diagnosis of hepatic The diagnosis of hepatic encephalopathy is made on al must in particular be included in the differential diag- encephalopathy on the basis of the clinical picture (see West Haven criteria) nosis of hepatic encephalopathy. Subdural haematoma the basis of the and must be considered in every patient with neuro- and other vascular processes, space-occupying clinical picture psychiatric disturbances and liver disease. The diagno- lesions, intoxication, encephalitis, hypothyroidism and sis is easy in known cases of cirrhosis of the liver or ful- metabolic disorders such as hypo- or hyperglycaemia, minating hepatitis but presents difficulties when the liver uraemia and hyponatraemia have all to be considered disease has not yet been diagnosed. as well. Clinico-chemical blood tests may be worthwhile in re- vealing a hitherto unsuspected liver disease or hyper- With hepatic encephalopathy, changes in the EEG are Electrophysiological ammonaemia syndrome, but have only limited rele- visible as abnormal slowing of the baseline activity investigations vance in the diagnosis of hepatic encephalopathy. although this is not pathognomic. Similar changes can be seen with uraemia, CO2 poisoning, vitamin B12 defi- The following summary proposed by Gerber and ciency, hypoxia or hypoglycaemia. In addition, it is dif- Schomerus indicates the relevant laboratory tests that ficult to evaluate changes because a reference EEG is may be useful in this context (Table 3.1). not usually available for the patient. It is often the case that no clear boundary can be drawn between normal Liver function tests Drug screening (urine and blood) and pathological. Similar restrictions exist in respect to • Transaminases (GOT, GPT) investigations with evoked potentials (VEP, P300). And Alcohol levels • Cholestasis parameters these methods are also relatively time consuming and Blood gas analysis (AP, γ−GT) expensive. Electrophysiological methods are therefore Fasting ammonia concentration not of prime importance in the diagnostic work-up of • Bilirubin • Total proteins with Cultures overt symptoms. electrophoresis/albumin (blood, urine, sputum, faeces) • Prothrombin time Hepatitis and HIV The main indication for imaging procedures in the Imaging techniques differential diagnosis of hepatic encephalopathy is the (CT, MRI etc.) Blood glucose Ascites (cells and culture) exclusion of other cerebral processes, especially Electrolytes Blood picture, C-reactive protein, cerebral haemorrhage. If symptoms corresponding to (with calcium and phosphate) erythrocyte sedimentation rate bleeding etc. are present, these imaging techniques Creatinine, urea are first-line investigations. Table 3.1: Laboratory tests in hepatic encephalopathy (after Gerber and Schomerus, 2000) 40 41
  • 22. Using specific test procedures and a standardized test Reduced fitness to Summary: drive, a study conducted recently by a research group drive in patients with Hepatic encephalopathy is diagnosed on the basis of the clinical picture. at the University of Hamburg, in collaboration with the subclinical hepatic The necessary investigations for the differential diagnosis of this condi- Föhrenkamp clinic of the Mölln BfA rehabilitation centre, encephalopathy tion include laboratory tests, imaging procedures and occasionally elec- showed that patients with cirrhosis of the liver and sub- trophysiological examinations. clinical hepatic encephalopathy were not completely fit to drive. Not only was their ability to drive a car severe- ly restricted but also the ability to adapt their driving 3.2 Early diagnosis behaviour to the general rules of the road, as can be seen in Figure 3.1 (Wein et al., 2002). Diminished Early recognition of hepatic encephalopathy is of partic- performance in ular clinical relevance, i.e. diagnosis in HE grade 0. subclinical hepatic Disturbances of consciousness are not yet noticeable Marks encephalopathy with minimal or subclinical hepatic encephalopathy but 5 SHE Group of patients with cirrhosis of the liver BF observing pedestrians without subclinical hepatic encephalopathy SI checking safe to proceed impairment of intellectual function already exists. This is SHE+ Group of patients with cirrhosis of the liver GEB observing speed with subclinical hepatic encephalopathy restrictions important to the patient for two reasons: KK Clinical control subjects BH observing obstacles 4 RB observing rules BL signalling • Recognition of incipient hepatic encephalopathy is an ZF rapid merging GEA adaptation of speed indication of the decompensation of the underlying 3 OW orientation by signposts VB observing right of way cirrhosis and the necessity of treatment. ABH maintaining distance • Even the existing limitations represent a risk to the 2 SP keeping in lane EP parking patient at work (especially manual occupations) or SE getting into the correct lane driving a car. AB hill starts 1 BEA obeying traffic lights BF SI GEB BH RB BL ZF GEA OW VB ABH SH EP SE AB BEA Reductions in performance such as slower reaction Figure 3.1: Test drive: Marks gained in driving categories (after Wein et al., 2002) times, inaccurate perception of geometric shapes and Note: Marks in school reports etc. in Germany are scored with 1 being the highest reduced visual selection abilities, which are at first bare- ly noticeable, are important at work or driving a car. In addition, there are personality changes such as reduc- ed emotional stability, loss of self-control and self-criti- Diminished function in minimal hepatic encephalopathy Psychometric cism as well as a tendency to dissimulate (Häussinger is best identified with the aid of psychometric tests. procedures in and Maier, 1996). The risks of a road traffic accident or Moreover, these tests are relatively easy and cheap to subclinical hepatic an accident during manual work are thereby increased. administer (see section 3.3). encephalopathy 42 43
  • 23. In certain cases, minimal hepatic encephalopathy in 42 patients with cirrhosis of the liver can also be recognized HE 0 in the EEG. Evoked potential tests (especially P 300) like- 40 SHE SHE wise show a certain diagnostic sensitivity for the early SHE diagnosis of hepatic encephalopathy. However, because CFF (Hz) 38 HE I the procedure has relatively high technical requirements, it is not generally used for routine diagnostic investigation. 36 HE I Critical flicker A procedure that has recently become established in the 34 frequency diagnostic investigation of hepatic encephalopathy is the 0 1 3 5 7 9 determination of the critical flicker frequency (CFF). In this Days test, the patient is shown a light that flickers with increas- Figure 3.3: CFF in patients with cirrhosis during and after recovery ing or decreasing frequency. With ascending frequency, from an episode of hepatic encephalopathy (Kircheis et al., 2002) the patient sees the light become constant (= fusion fre- quency). In the reverse procedure, the stable light starts to flicker as the frequency descends. The CFF is clearly Summary: altered in patients with subclinical hepatic encephalopa- The early diagnosis of hepatic encephalopathy in HE grade 0 is particu- thy compared with healthy people. As the severity of the larly important for the patient. Hitherto unrecognized diminution of per- condition increases, the CFF falls (Figure 3.2), and rises formance increases the risk of accidents at work or in road traffic. again with improvement in the HE episode (Figure 3.3) Psychometric tests are simple to administer and appropriate for the (Kircheis et al., 2002). early diagnosis of reduced intellectual function in hepatic encephalopa- thy. The determination of CFF is also very promising. 50 ns. ns. p < 0,01 p < 0,001 45 p < 0,001 p < 0,001 3.3 Criteria for assessing degree 40 p < 0,01 p < 0,001 of severity and monitoring the course of disease CFF (Hz) 35 Estimating the degree of severity of hepatic HE grade and 30 encephalopathy depends in the first line on the mental mental state state. This is evaluated on the basis of the patient’s 25 Controls HE 0 SHE HE I HE II clinical symptoms, in accordance with the HE grades of Conn and co-workers described above (see Table 2.1). Figure 3.2: CFF in patients with cirrhosis of the liver (Kircheis et 44 al., 2002) 45
  • 24. PSE index for The PSE index represents an extension developed by As a rule, in patients with hepatic encephalopathy, EEG monitoring progress Conn and co-workers (Conn and Bircher, 1994). In abnormal slowing of baseline activity and an increase in addition to the mental state (c.f. Table 2.1), this index amplitude can be seen in parallel with the degree of includes the semiquantative assessment of the symp- severity. Table 3.3 shows a semiquantitative classifica- tom of asterixis (Table 3.2), the time taken to complete tion of frequency for the PSE index. the number connection test (Table 3.4), the EEG (Table 3.3) and the ammonia concentration (Table 3.5). Grad- ing of each variable is weighted (mental state x3, each Grade 0 Alpha-frequency, 8.5–12 cycles per second (cps) of the others x1) and added together to give a maxi- Grade 1 7–8 cps mum PSE score of 28 points. The ratio of the individu- Grade 2 5–7 cps al score obtained to the maximum score gives the PSE Grade 3 3–5 cps index. The PSE index is more complex than the HE Grade 4 maximum 3 cps grading and is suitable for monitoring progress. Table 3.3: Semiquantitative grading of the EEG (after Conn and Bircher, 1994) Asterixis Even though asterixis (flapping tremor) as a sign of neu- romuscular disturbance is frequently present and is considered to be characteristic of hepatic encephalop- Many psychometric tests are used to establish Psychometric test athy, it is not actually specific to this condition. It also and quantify deterioration of intellectual function. This procedures appears with other disorders (e.g. intoxication, hypo- includes slowing down of the psychomotor perfor- magnesaemia etc.). From the clinical point of view, mance speed as well as restriction of both visual spatial however, it is suitable for diagnosing, evaluating the orientation and visual constructive ability. Validated and severity of the condition, and monitoring its progress. quantifiable psychometric test procedures which Table 3.2 shows a semiquantitative classification for the determine these deficits are the number connection PSE index. test (NCT) versions A and B, the digit symbol test (DST) and the line tracing test (LTT). Grade 0 No tremor From the practical point of view, a test should be sim- Grade 1 Rare tremor (1–2 per 30 seconds) ple to explain and quick to perform as well as quick and Grade 2 Occasional, irregular tremor easy to evaluate. Taking these points into consideration, (3–4 per 30 seconds) the number connection test (NCT) has proved itself to Grade 3 Frequent tremor (5–30 per 30 seconds) be a valuable tool (Conn and Bircher, 1994). Table 3.4 Grade 4 Virtually uninterrupted tremor present shows the standard forms used for versions A and B of Table 3.2: Semiquantitative grading of asterixis (flapping tremor) this test. (after Conn and Bircher, 1994) 46 47
  • 25. Figure 3.4: Number connection test, Versions A (NCT-A) and B (NCT-B). In NCT-A the numbers have to be Figure 3.5: (left) The line tracing test shows a complicated trace. Using a pencil, the patient has to rapidly fol- joined consecutively in numerical order (1,2,3…) as quickly as possible. In the more complicated NCT-B, low the original 5 mm wide track from beginning to end without going over the edges – at the same time, this the numbers and letters must be connected alternately numerically and alphabetically (1,A,2,B…). Evalu- is one way of testing “fitness to drive”. Evaluation considers both the time taken to complete the test and the ation of both tests is based on the time required to complete the test (Conn 1977) number of errors (Schomerus et al., 1981) Figure 3.6: (right) In the digit symbol test, the blanks should be filled in as quickly as possible with the sym- bols corresponding to the numbers given at the beginning. Evaluation depends on the total number of cor- Table 3.4 shows a semiquantitative grading of the time rectly inserted symbols within 90 seconds taken to perform the number connection test A for the PSE index. Figures 3.5 and 3.6 show the line tracing test As most forms of hepatic encephalopathy are associat- Ammonia and digit symbol tests. These are also evaluated accord- ed with an increased nitrogen load and/or reduced concentration ing to the time required to complete the sequences. detoxification of ammonia, the determination of the ammonia concentration in the blood provides diagnos- Grade 0 15–30 seconds tic evidence as well as an indication of the severity of the condition. Although the ammonia concentration in Grade 1 31–50 seconds arterial blood does not rise in strict proportion to the Grade 2 51–80 seconds severity of the hepatic encephalopathy, there is a posi- Grade 3 81–120 seconds tive linear correlation between these two parameters Grade 4 >120 (test cannot be carried out) (Conn and Bircher, 1994). Poor correlation may partly Table 3.4: Semiquantitative grading of the number connection test be attributed to difficulties with the analytical methods A (after Conn and Bircher, 1994) used. 48 49
  • 26. 4 TREATMENT OF HEPATIC ENCEPHALOPATHY In a recent study, it has been shown that a method not The management of hepatic encephalopathy depends customarily used (partial pressure measurement of mainly on the severity of the clinical picture. Intensive gaseous or “free” ammonia, which passes more easily medical care will be required as first line therapy in the into the brain) gives a closer correlation with the HE case of fulminating hepatic failure, while prophylactic grade than conventional measurements of the total measures to prevent progression and avoidance of pre- concentration of arterial ammonia (Kramer et al., 2000). cipitating factors need to be considered in the treat- ment of subclinical encephalopathy. Table 3.5 shows a semiquantitative grading of the arte- rial ammonia concentration for the PSE index. 4.1 General therapeutic concepts Grade 0 Within normal range (<60 µmol/l) The search for precipitating factors of hepatic encepha- Eliminating lopathy is of prime importance in both treatment of the precipitating factors Grade 1 1–1.33 x upper limit of normal acute case and prevention. Such factors play a role in Grade 2 1.33–1.67 x upper limit of normal 70-80% of patients (see section 2.2). Successfully elim- Grade 3 1.67–2.0 x upper limit of normal inating the most common precipitating factors – Grade 4 >2 x upper limit of normal gastrointestinal bleeding, azotaemia, sedatives, infec- tions and excessive protein consumption – may prevent Table 3.5: Semiquantitative grading of the arterial ammonia concentration (after Conn and Bircher, 1994) progression and overt symptoms in many cases. The most important measures that have to be considered stem from the need to eliminate these factors (Häussinger Summary: and Meier, 1996): Suitable means of classifying and monitoring the degree of severity of hepatic encephalopathy include the HE grading of the mental state and • Stop bleeding the PSE index, which also takes into account the semiquantitative grad- • Treat anaemia (aim: haematocrit = 30%) ing of other factors – asterixis, EEG, number connection test and ammo- • Treat acidosis with bicarbonate nia concentration. • Correct electrolytes to within normal range • Discontinue diuretics • Treat infections with antibiotics • Discontinue sedatives • Reduce protein intake • Make every effort to obtain abstinence from alcohol 50 51
  • 27. Knowledge of the precipitating factors is also very rele- 4.3 Drug therapy vant to prophylaxis against recurrence. By avoiding such factors (e.g. sedatives, alcohol, and excessive Although not yet elucidated in every detail, the Pharmacotherapeutic protein consumption) and early treatment (e.g. infec- neurotoxin ammonia plays an undisputed key role in the principles in hepatic tions) the progression of hepatic encephalopathy can pathogenesis of hepatic encephalopathy. As in the encephalopathy be positively influenced. past, the therapeutic objective is still the reduction of pathologically elevated levels of ammonia in the blood 4.2 Dietary therapy (see section 2.3). Regulation of An adequate diet is extremely important for patients The active substances used are selected principally in protein intake with hepatic encephalopathy and/or predisposing liver an effort to reduce ammonia production, promote disease. These patients often suffer from loss of appe- ammonia detoxification, correct the amino acid imbal- tite and do not consume enough calories. This poor diet ance and have a positive effect on neurodepression. favours protein catabolism which is associated with the increased formation of ammonia. Reduction in muscle Reduction of intestinal ammonia production mass disrupts extrahepatic ammonia detoxification Cleaning out the intestinal tract should eliminate nitro- since muscle tissue contributes to detoxifying ammonia genous substances from which ammonia is produced. (see section 1.1). Resistance to infection also falls with Non-absorbable disaccharides (e.g. lactulose) are inadequate nutrition. Active dietary therapy has a corre- mainly used for this purpose. Apart from their laxative spondingly favourable effect on the prognosis. actions, disaccharides also affect ammonia production in the intestinal flora. In bacterial metabolism, their With acute hepatic encephalopathy, the temporary breakdown products increase the incorporation of nitro- reduction of protein intake to 20-30 g/day is indicated. gen into bacterial proteins, so that less ammonia is re- The protein intake can then gradually be increased until leased; this in turn reduces the ammonia concentration a daily intake of 1 g/kg body weight is reached. Long- in the portal vein blood. Non-absorbable antibiotics term protein restriction which was previously mandato- (e.g. neomycin) are used to reduce the physiological ry is now considered obsolete. Such protein restriction flora in the large intestine and thus also to reduce the can only be justified in special cases of marked protein production of ammonia. intolerance. In the majority of cases an adequate balanc- ed diet improves the patent’s prognosis. Increase in extra-intestinal ammonia detoxification An important therapeutic means of increasing ammonia detoxification is stimulation of the urea cycle activity in the periportal hepatocytes and stimulation of glutamine 52 53
  • 28. synthetase in the perivenous hepatocytes (also known Effects on neurodepression as scavenger cells). L-ornithine-L-aspartate im- Inhibition of the GABA-ergic system with the group of proves the detoxification of ammonia by supplying aspar- substances known as benzodiazepine antagonists tate for glutamine synthesis in the perivenous scaven- (e.g. flumazenil) counteracts the neurodepressant ger cells. Ornithine promotes the urea cycle in the effects of the GABA-ergic activation. periportal hepatocytes. Both oral (6 g three times a day) and parenteral (20 g/day) administration of L-ornithine- With the exception of silymarin, the active substances Pharmacotherapeutic L-aspartate leads to a demonstrable reduction in hyper- mentioned above are currently used in clinical practice efficacy ammoniaemia as well as improvements in the impaired for the treatment of hepatic encephalopathy. Informa- mental functions of hepatic encephalopathy. tion on the efficacy of these substances has in the past been widely based on empirical findings and on the The use of benzoate is based on a different principle. results of studies where the methods used no longer This substance increases the excretion of ammonia. meet current research standards. Zinc is a co-factor of all the enzymes in the urea cycle. In the meantime, criteria for the demonstration of treat- Administration of zinc supplements should therefore ment efficacy have been drawn up for clinical trials. stimulate urea synthesis. Apart from general criteria (such as randomization, double-blinding, testing against placebo controls or A plant pharmaceutical, silymarin (an extract of milk standard drug therapy, and the inclusion of a sufficient thistle seeds), is used to protect the liver. Studies on this number of cases), the definition of efficacy criteria is of extract have shown that it prevents the entry of toxins particular relevance in studies on hepatic encephalopa- into liver cells, supports protein synthesis and stimu- thy. End points for demonstrating efficacy are basically lates regeneration of damaged hepatocytes. Lowering of clinical outcome measures such as the mental state (HE the blood ammonia concentration is not to be expected grade) and the PSE index which includes criteria such with silymarin. as psychometric tests and ammonia concentration (see section 3.3). Correcting the amino acid imbalance The administration of branched-chain amino acids Conducting such studies is made particularly difficult by (BCAA), i.e. leucine, isoleucine and valine, redresses the the great variability of symptoms and the spontaneous amino acid imbalance which adversely affects neuro- progression of hepatic encephalopathy. Even so, the transmitter metabolism in the brain and peripheral pro- necessary evidence of efficacy has in the meantime tein metabolism. been provided for some of the active substances in use today – forming the basis of “evidence-based medicine”. 54 55
  • 29. Evidence-based An evidence-based medicine review of the pharmaco- Acute HE: effectiveness of therapy of hepatic encephalopathy has been published • Elimination of precipitating factors: drug therapy recently. Studies with adequate methodology have GI bleeding, azotaemia, diuretics, sedatives, infections, increased been carried out for some of the substances (Table 4.1). dietary proteins, hypokalaemia and/or metabolic acidosis, hypo- volaemia, hypoxia, spontaneous bacterial peritonitis (SBP) • Measures to reduce ammonia concentration: Endoscopic control of bleeding, nasogastric lavage; oral lactulose (20- 50 ml x 3) or lactulose enema (300 ml in 1200 ml H2O) Therapeutic principle Active substance Results of placebo-controlled • Protein restriction: trials 0-30 g for max three days, then increase by 10 g/day to reach 1g/kg Reduction of intestinal Lactulose enema better than placebo body weight with sufficient calorie intake. ammonia production • Oral neomycin: Oral lactulose not definitively better than 50-100 mg/kg body weight/day in 3-4 divided doses if inadequate placebo (number of cases too response to lactulose small) • Flumazenil: Neomycin not better than placebo If the patient has previously been treated with benzodiazepines Increasing extra-intestinal L-ornithine-L-aspartate better than placebo • L-ornithine-L-aspartate (Hepa-Merz®): 60 g/day i.v. (max. 5 g/h) if the above measures have been un- ammonia detoxification successful Correcting amino acid Branched-chain amino better than placebo • Branched-chain amino acids (BCAA): imbalance acids (BCAA) By infusion, if the above measures have been unsuccessful Benzodiazepine receptor Flumazenil better than placebo • Paramomycin: antagonists 4 g/day in 2-4 divided doses or vancomycin (250 mg x 4) or Table 4.1: Drug therapy of hepatic encephalopathy. Evidence of efficacy from placebo-controlled metronidazole (400 mg x 2) trials (after Ferenci and Müller, 1999) • If the above are unsuccessful or the HE deteriorates, liver transplantation should be considered Chronic persistent HE This review shows that positive results from placebo- • Lactulose: 20-50 ml x 3 controlled trails are already available for some drugs. • Protein restriction – only if lactulose is ineffective: 1 g protein/kg body weight/day. If not tolerated, vegetable proteins or At the present time, the following recommendations are branched-chain amino acids (BCAA) oral 0.25 g/kg body weight/day made for the treatment of acute and chronic hepatic • L-ornithine-L-aspartate (Hepa-Merz®): 6-9 g/day x 3 encephalopathy (Table 4.2; after Caspary, 2001) • Prevention of precipitating factors (see above) • Consider indications for liver transplantation! Table 4.2: Treatment recommendations for acute and chronic hepatic encephalopathy (after Caspary, 2001) 56 57
  • 30. 5 MECHANISM OF ACTION AND PHARMACODYNAMICS OF HEPA-MERZ ® Further studies are in the planning stage and will be 5.1 Mechanism of action carried out with the aim of meeting the criteria of evi- dence-based medicine for the treatment of hepatic Detoxification of ammonia takes place predominantly in Stimulation of encephalopathy. the liver in the periportal and perivenous hepatocytes (see the urea cycle and section 1.1). Ammonia is converted to urea in the urea glutamine production cycle; ammonia reacts with glutamate to form glutamine in the liver (see Figure 1.2). Summary: L-ornithine-L-aspartate is able to promote the detoxifica- Treatment of hepatic encephalopathy includes intervening in the known tion of ammonia by stimulating disrupted urea and gluta- pathomechanisms. This includes the exclusion of precipitating factors mine synthesis (Figure 5.1) and correction of the dietary deficiencies that frequently exist. Pharma- cotherapy aims principally to reduce the ammonia production, promote ammonia detoxification, correct amino acid imbalance and counteract Perivenous hepatocytes Periportal hepatocytes neurodepression. In recent years – for reasons of quality assurance and Ornithine α-Ketoglutarate, Aspartate cost reduction – the requirements of evidence-based medicine have come to the forefront of medical practice. Such evidence of efficacy Cytosol Malate Cytosol definitely exists for L-ornithine-L-aspartate. Mitochondrion α-Keto- Mitochondrion Glutaminase glutarate Carbamyl- Glutamine phosphate Glutamine synthetase synthetase Glutamine Urea Glutamine Glutamine Urea Figure 5.1: Effects of L-ornithine-L-aspartate on urea and glutamine synthesis Urea synthesis is an irreversible liver-specific process, which takes place primarily in the periportal hepato- cytes. Ornithine activates the enzyme carbamyl phos- phate synthetase necessary for this process. Since orni- 58 59
  • 31. thine also acts as a substrate in urea synthesis, it is Effects of aspartate on glutamine synthesis: involved in the activation of the urea cycle in several - substrate for glutamine formation ways and thus in the irreversible (final) ammonia detoxi- fication. Through increased glutamine formation, the therapeutic Effects of ornithine on the urea cycle: administration of L-ornithine-L-aspartate (Hepa-Merz®) - substrate for urea synthesis also leads to an increase in ammonia detoxification in - activator of carbamyl phosphate synthetase the brain and muscles. This mechanism is of particular importance where there is a marked collateral circula- Aspartate and ornithine likewise support glutamine syn- tion or acute liver failure, when detoxification in the liver thesis. Glutamine synthesis (addition of ammonia to is reduced or temporarily ceases. glutamate) is localized to the perivenous hepatocytes. The prerequisite for this reaction is a sufficiently large supply of glutamate. As has recently been shown, aspartate (via α-ketoglutarate), glutamate and other dicarboxylates are taken up almost exclusively by peri- Summary: venous cells. By making aspartate available (after its The therapeutic administration of L-ornithine-L-aspartate (Hepa-Merz®) conversion into dicarboxylates) L-ornithine-L-aspartate increases ammonia detoxification in two ways: supplies the perivenous cells with substrates for the • Activation of the urea cycle in the liver by making available the meta- synthesis of glutamine. In this way, ammonia detoxifica- bolic substrates ornithine and aspartate. tion is increased through the formation of glutamine by • The substrates ornithine and aspartate promote the formation of the action of glutamine synthetase (Häussinger, 1990; glutamate and thus stimulate ammonia detoxification via glutamine Stoll and Häussinger, 1989; Häussinger et al., 1990; synthesis in the liver, brain and muscles. Stoll et al., 1991; Stoll and Häussinger, 1991). Ammonia detoxification via glutamine synthesis in the brain and muscle tissue makes an additional contribution to the ammonia reducing effects Stimulation of ammo- Reversible detoxification of ammonia via glutamine syn- of L-ornithine-L-aspartate in cases of hyperammonaemia when detoxifi- nia detoxification by thesis in the liver, brain and muscles (see section 1.1) is cation in the liver is by-passed or temporarily ceases. glutamine synthesis also increased by L-ornithine-L-aspartate. 60 61
  • 32. 5.2 Pharmacodynamic effects in The administration of L-ornithine-L-aspartate signifi- animal experiments cantly increased the activity of these two enzymes by 30% and 40% respectively, reaching almost normal 5.2.1 Effects of Hepa-Merz ® on levels. At the same time, there was a significant increase ammonia metabolism in the urea concentration of about 34%. The fall in the ammonia concentration was also significant (Figure 5.2). Experimental animal The effects of L-ornithine-L-aspartate on ammonia studies on ammonia metabolism have been investigated in many experimen- metabolism tal animal studies. Parameters such as the protective 800 8 effect against liver damage (induced by carbon tetra- ∗∗ 600 chloride, ammonium acetate or ammonium chloride), 7 Ammonia (µM) Urea (µM) reduction in ammonia levels and increase in urea syn- 6 400 thesis have been tested in various animal models 5 ∗ (mouse, rat, rabbit, dog) (Greenstein et al, 1956; Salva- 200 tore et al., 1959; Salvatore and Bocchini, 1961; Shioya 4 et al., 1964; Salvatore et al., 1964; Grossi et al., 1967; 3 0 Zicha and Zicha, 1968; Hermann, 1972; Zieve et al., C OA C OA 1986). As well as L-ornithine-L-aspartate, the individual Urea Ammonia components and other amino acids have sometimes Figure 5.2: Serum concentrations of urea and ammonia in cirrhotic been tested to compare their effects. In these studies, rats without (pink column) and with L-ornithine-L-aspartate (red ammonia metabolism tended towards normal and there column). Mean ± SEM given for each group; differences between test animals and untreated controls are significant at *p<0.03 and was a reduction in the ammonia toxicity on treatment **p<0.004 (after Gebhardt et al., 1997) with L-ornithine-L-aspartate. Activation of urea In a more recent study, the effects of L-ornithine- Examination of hepatocyte cultures from the two cycle enzymes by L-aspartate on hyperammonaemia and urea metabo- groups showed a higher urea production in the hepato- L-ornithine- lism in cirrhotic rats were investigated (Gebhardt et al., cytes from L-ornithine-L-aspartate-treated rats in com- L-aspartate 1997). Cirrhosis was induced by carbon tetrachloride parison with the untreated cirrhotic rats. It can be con- (CCl4). In cirrhotic animals, the activities of carbamyl cluded from these results that treatment of cirrhotic rats phosphate synthetase and arginase were lowered, indi- with L-ornithine-L-aspartate increases urea synthesis cating reduced functioning of the urea cycle. and thus the capacity to detoxify ammonia. 62 63
  • 33. 5.2.2 Effects of Hepa-Merz ® on effects of L-ornithine-L-aspartate on cerebral metabo- metabolism in the brain lism (in-vivo measurement of ammonia). In-vivo mea- surements were carried out by proton magnetic reso- Reduced NH3- con- To elucidate its mechanism of action, L-ornithine- nance spectroscopy (proton MRS) with special centration and over- L-aspartate was administered to rats with portocaval application and analysis procedures. This method coming amino acid shunts and hyperammonaemia induced by ammonium demonstrated a reduction in the ammonia with the imbalance in the brain acetate infusion (Vogels et al., 1995). This is a valid ani- administration of L-ornithine-L-aspartate, as well as a mal model of hepatic encephalopathy in subacute liver smaller rise in lactate and a slower increase in glutamine failure. In comparison with controls, significantly lower in comparison with controls. All changes were statisti- ammonia concentrations were measured in the blood cally significant. Even though the increase in glutamine (322 ± 40 vs 500 ± 32 mM, p<0.01) and in the brain and lactate in the brain in hyperammonaemia is well- (2.06 ± 0.2 vs 2.73 mM, p<0.05) following administra- known, it was not previously possible to investigate this tion of L-ornithine-L-aspartate. Lowering of serum in vivo. For the first time, these results demonstrated in ammonia levels could be attributed to the significantly vivo metabolic changes in the brain providing evidence higher urea synthesis in animals treated with L-ornithine- of the protective effects of L-ornithine-L-aspartate in L-aspartate. In this group, glutamine and glutamate in hyperammonaemia. the blood (signs of increased glutamine synthesis) were significantly higher than in the control group. In the The uptake of radioactively-labelled ornithine and Transport of ornithine cerebral dialysate, glutamate was significantly increased aspartate into the brain was investigated in a different into the brain while glutamine showed a trend towards higher levels. animal model (Albrecht et al., 1994). Acute hepatic Both in the blood and brain the ratio between encephalopathy was induced in rats by hepatotoxic branched-chain amino acids and aromatic amino acids thioacetamide. Substance uptake was given by the brain (BCAA/AAA) tended towards normal, mainly due to the uptake index (BUI) calculated from the radioactivity reduction of aromatic amino acids. With respect to the measured and administered. The BUI was investigated criteria for encephalopathy (EEG, clinical grading) these in three stages: a coma stage (3 administrations of were less pronounced on treatment with L-ornithine- thioacetamide) a milder stage (2 administrations) and a L-aspartate, although the differences did not reach sta- group with induced hyperammonaemia (ammonium tistical significance. acetate) without liver damage. In the coma group, the BUI for ornithine increased after 24 hours to 275% of In-vivo measurement A further study carried out by Slotboom et al. (1994) in control levels and milder stages, to 220% of control of ammonia in the the same animal model reported on the additional levels after 7 days and 442% after 21 days (each sig- brain nificant at p<0.05). 64 65
  • 34. Induced hyperammonaemia did not lead to increased relevant changes for lysine. From these study results, uptake of ornithine into the brain. the authors concluded that the transport system across the blood-brain barrier is modified by as yet unidentified Aspartate is not normally transported across the blood- factors, possibly released by the damaged liver. The g+ brain barrier. The BUI for L-aspartate did not increase in transporter which normally gives preference to arginine any of the three stages, an indication that the blood- may change in structure or conformation to preferen- brain barrier remains intact in this animal model. tially transport ornithine, or a normally latent ornithine- specific transport system is activated. It can be concluded from the results of this study that ornithine administered therapeutically in the form of The protective effects of L-ornithine-L-aspartate and Coma-protective L-ornithine-L-aspartate is taken up into the brain in cases the possible mechanism of action were investigated in effects through of hepatic encephalopathy, probably through activation rats with portocaval shunts and hyperammonaemia stimulation of central of the transport system across the blood-brain barrier. induced by ammonium acetate infusion (Rose et al., and peripheral ammo- 1998). It was shown that L-ornithine-L-aspartate infu- nia detoxification Transport system for Using the same animal model (hepatic encephalopathy sions could prevent ammonium acetate-induced coma ornithine and arginine induced by 2 doses of thioacetamide), this research in all animals. None of the rats treated with L-ornithine- across the blood- group conducted a further study to investigate the L-aspartate showed any deterioration of neurological brain barrier transport system for ornithine across the blood-brain status under these conditions although all the non- barrier in more detail (Albrecht et al., 1996). Ornithine treated animals did. passes across the blood-brain barrier in the same way as the other two dibasic amino acids, arginine and ly- These protective effects of L-ornithine-L-aspartate were sine, via a common saturatable transport system (g+ associated with a smaller rise in ammonia levels in the transporter). The objective of the study was to deter- blood and an increase in the urea concentration mine whether the BUIs of radioactively-labelled orni- (p<0.01 and p<0.05 vs controls). In both plasma and thine, arginine and lysine were different in this model cerebrospinal fluid (CSF), concentrations of glutamate of hepatic encephalopathy. and glutamine were significantly higher than in the con- trol animals. The branched-chain amino acids were The BUI for ornithine increased to 186% after 7 days higher in the plasma than in the control group, but only and to 345% after 21 days in comparison with the leucine was higher in the CSF. untreated controls (p<0.05 vs controls in both cases). The corresponding values for arginine were 30% and These results show the protective effects of L-ornithine- 42%, respectively (p<0.05 vs controls in both cases), L-aspartate with respect to hyperammonaemia-induced i.e. transport into the brain decreased. There were no coma. The mechanism of action consists on the one hand 66 67
  • 35. of peripheral stimulation of urea and glutamine synthesis Coma appeared in the control groups after about 11 and increased central glutamine synthesis on the other. hours but not until 15 hours with L-ornithine-L-aspartate infusions (p<0.02). The water content of brain tissue Protective effects In acute liver failure (ALF) the development of cerebral was significantly less in the L-ornithine-L-aspartate- of Hepa-Merz® in oedema with raised intracranial pressure and cerebral treated animals than those given saline infusions and cerebral oedema herniation are the most important causes of death. The approached levels in the control animals (Figure 5.4). effects of L-ornithine-L-aspartate were tested in an ani- mal model of acute liver failure, induced by hepatic p < 0.05 devascularisation (Rose et al., 1999). In this model, 83,0 p < 0.001 p < 0.001 treatment with L-ornithine-L-aspartate infusions led to 82,5 % water in brain tissue plasma ammonia concentrations approaching normal in 82,0 comparison with controls (Figure 5.3). The appearance 81,5 of signs of severe encephalopathy – defined as pre- 81,0 coma and coma, in accordance with the degree of 80,5 severity – were significantly delayed. 80,0 79,5 700 L-ornithine-L-aspartate infusion 79,0 Saline infusion Controls ALF ALF Ammonia concentration 600 saline OA in plasma (µg/dl) 500 infusion infusion 400 Figure 5.4: Effects of L-ornithine-L-aspartate (OA) infusions on the 300 water content of the brain tissue in comparison with normal controls * and animals given saline infusions in a model of acute liver failure 200 (ALF) with encephalopathy. The individual values are shown with ** 100 ** means (horizontal lines) for each group as well as the differences between the groups (p<0.01, p<0.05) (after Rose et al. 1999) 0 Baseline +6 hours Pre-coma Coma Administration of OA or saline The observed protective effects of L-ornithine-L-aspar- Figure 5.3: Effects of L-ornithine-L-aspartate infusions on the plas- tate were accompanied by increased plasma concen- ma ammonia concentration in comparison with controls given sa- line infusions in a model of acute liver failure with encephalopathy. trations of glutamate, γ−aminobutyric acid (GABA), tau- The first measurement after baseline was taken 6 hours after liga- rine and alanine as well as the branched-chain amino tion of the hepatic artery. The stages of pre-coma and coma were acids leucine, isoleucine and valine. Increased gluta- defined on the basis of the neurological status. The means ± SE are shown for each group. Differences between the groups are statisti- mate concentrations deliver the substrate for ammonia cally significant at *p<0.05 and **p<0.01 (after Rose et al., 1999) detoxification via glutamine synthesis. In agreement 68 69
  • 36. with this, glutamine in the plasma was significantly rais- ed (p<0.02), indicating increased glutamine synthesis in Summary: the muscles. Also in agreement, direct measurement of Results of animal experiments carried out in models of the various forms glutamine synthetase in the muscle showed that the of encephalopathy in hyperammonaemia and acute liver failure show the activity of this enzyme was doubled in animals treated protective effects of L-ornithine-L-aspartate with respect to hyperam- with L-ornithine-L-aspartate. In this animal model of monaemia and encephalopathy. Various methods have shown the acute liver failure, increased glutamate concentrations mechanisms of action to be the lowering of the ammonia concentrations can regularly be demonstrated in the extracellular fluid in the blood and brain. The reasons for this are increased urea synthesis of the brain. It is therefore assumed that this contributes in the liver and stimulation of glutamine synthesis which has been to the development of cerebral oedema in acute liver demonstrated in the muscle and sometimes also in the brain. Transport failure. Lowering of the CSF glutamate levels by 60% as of ornithine across the blood-brain barrier has been demonstrated. Orni- seen in this experiment and the concurrent reduction in thine contributes to the observed therapeutic effects possibly by the water content support this hypothesis. Glutamine in the promotion of glutamate formation in the brain. CSF remains virtually unchanged. Results in animal models of acute liver failure with en- cephalopathy show the ammonia-lowering effects of L-ornithine-L-aspartate together with a protective effect against the development of cerebral oedema and ence- phalopathy. Lowering of the ammonia can be attributed to increased ammonia detoxification through stimula- tion of glutamine synthesis in the muscles. 70 71
  • 37. 6 CLINICAL RESULTS WITH HEPA-MERZ ® Experimental clinical studies Authors Study design Duration- No. of Aetiology of Test drug/placebo Efficacy of L-ornithine-L-aspartate of study patients hyperammonaemia or control Henglein-Ottermann 1976 Rd pc 90 min 20 Cirrhosis; administration of an OA i.v. (5 g/h) vs 10% sorbitol - ammonia-lowering effect crossover, NH4Cl infusion (placebo) intra-individual Leweling et al. 1991 Rd db pc 8h 10 Cirrhosis; induction of OA i.v. (5, 20, 40 g/day) vs - dose-dependent reduction of ammonia in blood, increase in crossover hyperammonaemia by 0.9% NaCl (placebo) BCAA/AAA ratio design protein consumption Reynolds et al. 1999 Rd pc 7 days 16 Cirrhosis OA i.v. (40 g/8h) vs placebo - increased rate of protein synthesis in muscle after meals - inhibition of catabolic metabolism in muscles Rees et al. 2000 Rd pc 60 min 8 Cirrhosis, oral glutamine OA i.v. (5 g/h) vs placebo - suppression of expected rise in ammonia load (20 g) - stabilization of psychometric functions Delcker et al. 2002 Open 24 h 15 Cirrhosis OA i.v. (40 g/8h) - decrease in arterial NH3 concentration and in glutamate + glutamine/ HE I, II creatine ratios - close correlation of both parameters Clinical Trials with intravenous L-ornithine-L-aspartate Authors Study design Duration- No. of Aetiology of Test drug/placebo Efficacy of L-ornithine-L-aspartate of study patients hyperammonaemia or control Kircheis et al. 1997 Rd db pc 7 days 126 Cirrhosis OA i.v. (20 g/day) - improvement of mental function vs 5% fructose (placebo) - reduction in time required for NCT - ammonia-lowering effect Feher et al. 1997 Rd pc db 7 days 80 Cirrhosis OA i.v. (20 g/4h) vs placebo - reduction in ammonia levels Clinical Trials with oral L-ornithine-L-aspartate Authors Study design Duration- No. of Aetiology of Test drug/placebo Efficacy of L-ornithine-L-aspartate of study patients hyperammonaemia or control Stauch et al. 1998 Rd db pc 14 days 66 Cirrhosis OA oral (3x 6 g/day) - improvement of mental function vs placebo - reduction in time required for NCT - ammonia-lowering effect Liehr et al. 1992 Rd controlled 14 days 42 Cirrhosis OA oral (3x 9 g/day) - effects of OA and lactulose with respect to improvement vs lactulose oral (3x 30 ml) of mental function - reduction in time required for NCT and lowering of ammonia Table 6.1: Controlled clinical trials with Hepa-Merz®(L-ornithine-L-aspartate, OA) in patients with Rd: randomised; db: double-blind; pc: placebo-controlled hyperammonaemia and hepatic encephalopathy 72 73
  • 38. 6.1 Clinical research with clinical practice (GCP) etc. In this way the requirements Hepa-Merz ® for evidence-based medicine (see section 4.3) are also clearly met for treatment with Hepa-Merz® (L-ornithine- Clinical research with The clinical efficacy of Hepa-Merz® (L-ornithine- L-aspartate). Hepa-Merz® and L-aspartate) in liver diseases has already been compre- evidence-based hensively investigated and reported in therapeutic 6.2 Experimental clinical studies medicine observations and clinical trials (Kalk, 1958; Kosozu with Hepa-Merz ® 1966; Schäfer, 1968; Aschke,1969; Melzer et al., 1969; Vorberg, 1969; Baumann, 1970; Schmitt and Ziegler, 6.2.1 Effects of Hepa-Merz ® on 1970; Wotzka and Weber, 1972; Leonhardt and Bun- ammonia concentration gert, 1972; Hunold, 1973; Schmidt, 1974; Müting and Reikowski, 1980; Hendricks and Hellweg, 1984; Müller- From a very early stage, measurement of the ammonia Ammonia Kengelbach, 1986; Müting et al., 1988; Handschuh, concentration has been included in clinical studies as a concentrations 1990; Müting et al., 1992; Podymova and Nadinskaya, key feature of the mechanism of action. Changes in the in clinical studies 1998). In these studies the use of Hepa-Merz®, as infu- ammonia concentrations on treatment with L-ornithine- with Hepa-Merz® sion, oral administration or a combination of the two, L-aspartate were closely related to the clinical thera- was documented in patients with mild to severe liver peutic efficacy (Schmitt and Ziegler, 1970; Leonhardt insufficiency. The underlying cause of hepatic dysfunc- and Bungert, 1972; Müting and Reikowski, 1980, tion was most often cirrhosis, although patients with Müting et al., 1992). In the majority of the more recent other liver diseases were also treated. The documented clinical studies, the ammonia concentration was also duration of the studies ranged from a few days to sev- determined, that is to say, was one of the main out- eral years. come measures. In the following controlled experimen- tal clinical studies, various aspects of the effects of In the past few years, clinical trials on the efficacy and L-ornithine-L-aspartate on hyperammonaemia were tolerability of Hepa-Merz® (L-ornithine-L-aspartate) investigated. have been conducted in accordance with general methodological advances in clinical research and evi- In a controlled clinical study, ammonia concentrations in Controlled clinical dence-based medicine (see sections 6.3 and 6.4). venous blood were investigated after hyperammon- studies with These include, in particular, criteria such as placebo aemia had been experimentally induced in patients with experimental controls, double blind conditions, randomized alloca- cirrhosis and in healthy volunteers, with and without the hyperammonaemia tion to treatment arms, sufficient numbers of patients administration of L-ornithine-L-aspartate (Henglein- according to estimates of the number of cases requir- Ottermann, 1976). For this purpose, hyperammon- ed, conduction of the trial in accordance with good aemia was induced in 10 patients with cirrhosis and 10 74 75
  • 39. healthy volunteers by giving them ammonium chloride + NH4 (µg/dl) ✱ p < 0.05 x ± SEM infusions (40 mg/kg body weight over 60 minutes) and 800 load-response curves were plotted from the blood sam- L-ornithine-L-aspartate (5 g/h) ples taken over a total of 2 hours. As expected, the NH4CI infusion (40 mg/kg BW) ✱ 600 concentrations in cirrhotic patients were statistically sig- nificantly higher at all times than in the healthy test sub- jects (peak levels in each case were reached 60 mi- 400 nutes after the start of the infusion). The infusion was repeated on another day in the study, but this time with 200 the additional administration of 5 mg L-ornithine- L-aspartate (randomized test sequence). This showed 0 that the higher peak ammonia concentrations mea- sured in the cirrhotic patients after 60 minutes could be 0 30 50 60 70 90 120 significantly reduced by the administration of L-ornithine- Time (min) after the NH4CI infusion L-aspartate (p≤0.05) so that the overall load-response NH4CI NH4CI + OA curve was flatter. As expected, administration of L-ornithine-L-aspartate made no difference to the Figure 6.1: Effects of Hepa-Merz® on the hyperammonaemia induc- ed by ammonium chloride infusion (40 mg NH4Cl/kg BW) in ammonia concentrations in people with healthy livers patients with cirrhosis of the liver (Figure 6.1). Lowering of ammonia Ammonia loading demonstrated the reduced detoxifica- study with a four-way crossover design (Lewling et al, in patients with tion ability of the cirrhotic liver though an – in contrast to 1991, Staedt et al., 1993). Ten patients with cirrhosis of cirrhosis the healthy liver – overall higher concentration of am- the liver and hyperammonaemia (postprandial >120 monia in the blood with a more prolonged duration, µg/dl) each underwent four test procedures in varying which could be significantly lowered by the administra- order. An 8-hour infusion containing 5 g, 20 g or 40 g of tion of L-ornithine-L-aspartate, especially the peak L-ornithine-L-aspartate or placebo was given during values. each treatment unit, so that, by the end of the study, data were available for analysis from each patient at Dose-dependent The dose-effect relationships of L-ornithine-L-aspartate each of the four doses. Two protein loads were given on effects on postprandi- to the physiological postprandial hyperammonaemia each study day, similar to normal dietary habits: 0.25 al hyperammonaemia and the amino acid profile in the plasma were investi- g/kg body weight in the mornings and 0.5 g/kg body gated in a randomized double-blind, placebo-controlled weight at lunchtime. 76 77
  • 40. Analysis of the ammonia concentration from venous with L-ornithine-L-aspartate than with placebo; with a blood showed that, in comparison with placebo, post- dose of 40 g, the difference in peak levels at 11 o’ clock prandial hyperammonaemia was lowered by the admin- was statistically significant. The analysis also showed istration of L-ornithine-L-aspartate in a dose-dependent that, compared with placebo, L-ornithine-L-aspartate manner, and with the highest dose it was almost pre- caused a significant rise in serum urea, a sign of increas- vented (Figure 6.2). All postprandial values were lower ed ammonia detoxification. ✱ p < at 9:00 ✱ p < at 13:00 The amino acids alanine, arginine, glutamate, glutamine Amino acid profile and p < at 9:00 p < at 13:00 + + ✱✱ NH4 (µg /dl) ✱✱ NH4 (µg /dl) and proline which are metabolically linked to the met- peripheral metabolism 400 400 abolism of ornithine and aspartate, increased markedly ✱ ✱✱ under the administration of L-ornithine-L-aspartate, sometimes in a statistically significant manner when 350 350 compared with placebo. On the other hand, the amino ✱ acids methionine, phenylalanine, tyrosine, threonine, ✱ 300 ✱✱ 300 serine and glycine were reduced in a dose-dependent ✱✱ manner. The reduction in these amino acids, which are not metabolically closely associated with L-ornithine- 250 250 L-aspartate, may be interpreted as peripheral retention (decreased release or increased uptake in the periphery). 200 200 The authors discuss the effects as an indication of the improvement in protein equilibrium and an anticatabolic effect of L-ornithine-L-aspartate in muscle tissue as a 150 ➨ 150 ➨ Protein load Protein load contribution to the observed lowering of ammonia. (0,25 g/kg BW) (0,5 g/kg BW) A supplementary evaluation of the study data (Staedt et al., 1993) quantified the relationship of branched-chain 100 100 9 11 13 hours 13 15 17 hours amino acids (BCAA) to aromatic amino acids (AAA). In patients with cirrhosis, there is often a shift in the equilib- Placebo OA (5g) OA (20g) OA (40g) rium between these two groups, in favour of the aro- matic amino acids (see section 2.2.3). After protein load- Figure 6.2: Venous ammonia concentrations (median ± SEM) with infusions of Hepa-Merz® at doses of 5 g, 20 g and 40 g and placebo, with protein loading at 9:00 and 13:00 hours. Postprandial hyperam- ing, the mean BCAA/AAA quotient under placebo clearly monaemia (significant increases at 11:00 and 15:00 on placebo) were prevented at 15:00 with 20 g fell from 1.6 to 1.2. With the administration of and at 11:00 and 15:00 with 40g L-ornithine-L-aspartate. Peak values measured at 11:00 with 40 g OA L-ornithine-L-aspartate (40 g), however, the quotient were significantly lower than with placebo (after Staedt et al., 1993) was increased from 1.4 to 1.5. This result is a sign that 78 79
  • 41. the amino acid imbalance tends towards normal on However the increase seen on treatment with L-ornithine- treatment with L-ornithine-L-aspartate. L-aspartate was significantly less than with placebo (Figure 6.3). The results of these controlled studies demonstrated that the effects L-ornithine-L-aspartate on postprandial 100 hyperammonaemia are dose-dependent. In addition, 80 62 µmol/l they showed that L-ornithine-L-aspartate causes chang- Ammonia µmol/l es in the amino acid profile that can be interpreted as 60 anticatabolic actions, as well as having a positive effect 36 µmol/l 40 on the preexisting imbalance between branched-chain and aromatic amino acids found in patients with cir- 20 rhosis. 0 L-ornithin-L-aspartate Placebo Increase in ammonia With hepatic insufficiency, the ammonia concentration and reaction times in the blood rises to unphysiological levels after a pro- Figure 6.3: Venous ammonia concentration after protein loading after protein loading, tein meal. A controlled clinical study was carried out to (20 g glutamine) on treatment with Hepa-Merz® (left) and placebo (right) in patients with cirrhosis of the liver. Figures shown are the compared with investigate whether, due to its specific effects, the mean values (after Rees et al., 2000) placebo administration of L-ornithine-L-aspartate protected against a rise in ammonia after protein loading and, as Parallel to the inhibition of the ammonia increase after a result, had a positive effect on psychometrically protein loading, the administration of L-ornithine- measurable functional deficiencies (Rees et al., 2000). L-aspartate stabilized psychometric functions. While Eight patients with cirrhosis of the liver were each the reaction time to a visual stimulus (choice reaction subjected to two loading tests with 20 g glutamine. In time, CRT) was significantly prolonged after a protein randomized sequence, either 5 g L-ornithine-L-aspartate load and placebo, there was no prolongation of reaction or placebo was infused concurrently. Ammonia time when L-ornithine-L-aspartate was administered concentrations in the blood were determined before (Figure 6.4). and after the glutamine load and psychometric tests performed at the same time. The results of these controlled clinical studies show that the administration of L-ornithine-L-aspartate counter- As expected, the glutamine load caused an increase in acts metabolic disturbance after a protein meal in venous ammonia, the baseline being 27 ± 5 µmol patients with cirrhosis and, in parallel to this, the (mean ± SEM). psychometric functions remain stable. 80 81
  • 42. the start of treatment and 7 days afterwards, the protein L-ornithine-L-aspartate Placebo 450 synthesis rate in muscle was tested both in a fasting 416 state and after the ingestion of food, using a special 406 404 Reactiontime in ms procedure (leucine incorporation). The results of the 400 390 study showed a return to the normal response on L-ornithine-L-aspartate, with a significant increase in the protein synthesis rate in muscle after the ingestion 350 of food from 0.044 ± 0.009 to 0.071 ± 0.022% per hour (mean ± SEM, p=0.06). In contrast, there were no 300 changes on placebo treatment. Under fasting condi- before after before after tions, the protein synthesis rate in muscle was further glutamine load glutamine load reduced on placebo while it stabilized on L-ornithine- Figure 6.4: Reaction time in choice reaction test (CRT) before and L-aspartate (Figure 6.5 and Table 6.2). after protein loading (20 g glutamine) on Hepa-Merz® (left) or pla- cebo (right) in patients with cirrhosis of the liver. Figures shown are OA group Placebo group the mean values (after Rees et al., 2000) fasting after food fasting after food Day 1 0.051 (0.015) 0.044 (0.009)* 0.047 (0.016) 0.046 (0.016) Day 7 0.047 (0.015) 0.071 (0.022)* 0.035 (0.012) 0.049 (0.023) 6.2.2 Effects of Hepa-Merz ® on Tab. 6.2: Protein synthesis rate (%/h) in muscle of cirrhotic patients; protein synthesis in muscle means (SEM) *p=0,06 Protein synthesis Muscle wasting is a characteristic symptom in cirrhosis %/h rate in muscle in of the liver and is, as a rule, associated with an unfa- 0,03 L-ornithine-L-aspartate Placebo comparison with vourable prognosis. In people with healthy livers, the 0,025 placebo rate of protein synthesis in muscle tissue rises after the 0,02 intake of food, whereas this increase is lacking or Protein synthesis 0,015 reduced in cirrhotic patients. A controlled clinical study 0,1 (Reynolds et al., 1999) was carried out to investigate 0,005 whether, because of its favourable effects on the metab- 0 0,027 0,003 OA (fasting) -0,005 olism of ammonia and amino acid equilibrium, L-orni- -0,004 OA (posprandial) -0,01 Placebo (fasting) thine-L-aspartate also beneficially influenced protein -0,012 Placebo (posprandial) -0,015 metabolism. Sixteen patients with cirrhosis of the liver fasting posprandial fasting posprandial and muscle wasting were randomized to infusions of 40 g Fig. 6.5: Representation of the values from Tab. 6.2 as the difference L-ornithine-L-aspartate or placebo for 7 days. Prior to between day 1 and day 7 82 83
  • 43. The results can be interpreted as the inhibition of catabolic given an infusion of 40 g L-ornithine-L-aspartate. Imme- muscle metabolism and stimulation of protein synthesis in diately before and 6 hours after the start of the infusion, the muscle due to L-ornithine-L-aspartate. MRS investigations were carried out in the parietal region and at the same time, the arterial ammonia con- 6.2.3 Effects of Hepa-Merz ® on centration was determined. neurometabolites It was shown that the ammonia concentration in arteri- Ammonia and Neurometabolites in the brain can be demonstrated in vivo al blood and the Glut+Gln/Cr ratio in the brain correlat- neurometabolites using proton magnetic resonance spectroscopy (proton ed in a statistically significant manner (r = 0.72, in the brain MRS) (Delcker et al., 2002). The typical changes seen in p<0.001). Both parameters decreased with the infusion hepatic encephalopathy relate in particular to the concen- of L-ornithine-L-aspartate, and the extent of these tration of glutamine which is increased in the brain – possi- changes also correlated in a statistically significant bly as a result of the increased ammonia in the blood and manner (r = 0.54, p<0.04). Figure 6.7 shows NMR the stimulation of glutamine synthesis in the astrocytes spectra before and after the infusion of Hepa-Merz®. (Figure 6.6). Gln Glu Glu + Gln Glu + Gln prior to ornithine aspartate infusion after ornithine aspartate infusion 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 Figure 6.6: Characteristic neurometabolite concentrations in ppm ppm patients with hepatic encephalopathy In an open study, it was investigated whether the ratio Figure 6.7: Nuclear magnetic resonance spectra before and after Hepa-Merz® infusion. On the right a clear lowering of the glutamate and glutamine concentrations in the brain can be seen following the infusion of glutamine + glutamate in relation to creatine (Glut+Gln/Cr) changed when L-ornithine-L-aspartate These results confirm that, in parallel to the reduction in was given, and whether this ratio correlated with the ammonia concentration, L-ornithine-L-aspartate has an lowering of the ammonia concentration seen with effect in reducing the glutamine and glutamate concen- L-ornithine-L-aspartate. With these objectives, fifteen trations in the brain. At the same time, this investigation patients with grade I/II hepatic encephalopathy were presents a new parameter for clinical studies on hepatic 84 85
  • 44. encephalopathy which can be used in vivo to deter- parameters were the HE grade, the PSE index and the mine quantitative changes in neuro-metabolites in the venous ammonia concentration under fasting condi- brain. tions. 6.3 Clinical results with intra- The results of venous ammonia concentrations showed Fasting and venous Hepa-Merz ® therapy statistically significant differences in favour of L-ornithine- postprandial L-aspartate (Figure 6.8). The mean values under fasting ammonia 6.3.1 Hepa-Merz ® infusion in conditions before the start of treatment were 81 ± 38 concentrations comparison with placebo µmol/l in the L-ornithine-L-aspartate group and 83 ± 43 µmol/l in the placebo group. After seven days they had Placebo-controlled A multicentre randomized double-blind placebo-con- decreased on average by 17 ±37 µmol/l and 6 ± 32 double-blind trial on trolled trial was carried out to demonstrate the efficacy µmol/l, respectively (before/after comparison). The 126 patients with and tolerability of L-ornithine-L-aspartate infusion con- group differences in favour of L-ornithine-L-aspartate cirrhosis of the liver centrate (Kircheis et al., 1997). One hundred and twen- therapy were statistically significant after 4 and 7 days and HE grade 0 ty-six patients with cirrhosis of the liver and chronic (p=0.0155 and p=0.0188). The mean postprandial (subclinical) to II (persistent) overt hepatic encephalopathy (grades I/II, ammonia concentration of 83 ± 37 µmol/l initially mea- West Haven criteria) or subclinical hepatic encephalop- sured in the L-ornithine-L-aspartate group was lower athy (SHE and performance time for number connec- than that of 91 ± 48 µmol/l in the placebo group. After tion test A >30 seconds) were enrolled. In addition, all 7 days’ treatment the mean postprandial ammonia con- patients had to have demonstrable hyperammonaemia centrations had decreased by 16 ± 40 µmol/l and by 10 (venous ammonia concentration >50 µmol/l). ± 36 µmol/l, respectively. The group differences in favour of L-ornithine-L-aspartate treatment were signifi- The patients were given daily in-patient treatment for cant on days 2 and 4 (p<0.013) and showed a tenden- seven days, receiving an infusion of 20 g L-ornithine- cy towards significance on day 7 (p=0.078). L-aspartate (4 ampoules infusion concentrate) dissolv- ed in 250 carrier solution over 4 hours (N=63), or a cor- Statistically significant group differences in the time Performance time responding placebo infusion (N=63). At the same time required for the NCT-A were also seen in favour of for the number they were given a diet containing 1 g protein/kg body L-ornithine-L-aspartate treatment (Figure 6.9). connection test weight per day divided into three meals. Investigations A sub-evaluation of the degree of severity of the hepat- were carried out before the start of treatment (time 0) ic encephalopathy showed that the group differences and after 2, 4 and 7 days. The main efficacy parameters with grade II were the most pronounced, but were also were the postprandial venous ammonia concentration significant with subacute hepatic encephalopathy (SHE) HE grading and the time required for NCT-A. Further efficacy and grade I. The mental state recorded on the basis of and PSE index 86 87
  • 45. 160 100 ** *** Fasting ammonia (µmol/l) 140 * ** * 80 * 120 NCT-A (seconds) *** ** *** P 75 100 P 75 60 Mittelwert 80 Mittelwert Median Median 60 P 25 40 P 25 40 20 20 *p < 0.05, **p > 0.01, ***p < 0.001 *p < 0.05, **p > 0.01, ***p < 0.001 0 0 0 2 4 7 0 2 4 7 0 2 4 7 0 2 4 7 Duration of treatment (in days) Duration of treatment (in days) 160 Postprandial ammonia (µmol/l) Mean ±SD OA (P25 bis P75) 140 * Median Placebo (P25 bis P75) 120 * ** P 75 100 *** Figure 6.9: Effects of L-ornithine-L-aspartate (left) versus placebo Mittelwert 80 Median (right) on the time required to perform the number connection test. 60 P 25 Figures given are the mean (black square) and standard deviation, median (white square), 25th and 75th percentiles and the group dif- 40 ferences between the two treatments (after Kircheis et al., 1997) 20 *p < 0.05, **p > 0.01, ***p < 0.001 0 0 2 4 7 0 2 4 7 the changes in the HE grade after 7 days’ treatment Duration of treatment (in days) with L-ornithine-L-aspartate. With HE grade 0, a reduc- Mean ± SD OA (P25 to P75) tion in the NCT performance time from the baseline Median Placebo (P25 to P75) value to <30 s was taken as evidence of improvement. Figure 6.8: Reduction in ammonia levels (µmol/l) over a period of 7 L-ornithine-L-aspartate was clearly superior to placebo. days on treatment with L-ornithine-L-aspartate (left) versus placebo (right). Figures given are the mean (black square) and standard devia- tion, median (white square), 25th and 75th percentiles and the group In addition, changes in the modified PSE index were differences between the two treatments (after Kircheis et al., 1997) evaluated. HE grade, venous ammonia concentration and NCT performance time were taken into account in clinical criteria (HE grade) improved more clearly after 7 the calculation. The mean of the PSE index at the start days’ treatment with L-ornithine-L-aspartate (from of treatment was 0.28 ± 0.12 in both the L-ornithine- mean 0.97 ± 0.53 to 0.42 ± 0.33) than on placebo (0.91 L-aspartate and the placebo groups. By the end of ± 0.48 to 0.72 ± 0.52). Statistical analysis showed sig- treatment (day 7), it had fallen to 0.135 ± 0.10 in the nificant differences between the groups (p<0.001) in L-ornithine-L-aspartate group and to 0.22 ± 0.14 on favour of L-ornithine-L-aspartate. Figure 6.10 shows placebo. Both the comparison of treatments on day 7 88 89
  • 46. • 1 patient was excluded before the start of the trial Patients with improvement in HE grade N 40 37 because of non-cooperation L-ornithine-L-aspartate 35 Placebo group: Placebo 30 • 1 patient with advancing cardiac failure 25 20 19 20 In the three patients (5%) with gastrointestinal symp- 15 12 9 9 toms or nausea/vomiting, a causal relationship with the 10 6 L-ornithine-L-aspartate infusion cannot be ruled out. 5 2 0 Overall HE HE SHE The results of the double-blind trial show the efficacy of grade II grade I L-ornithine-L-aspartate in comparison with placebo Figure 6.10: Number of patients with improvement in the HE grade with respect to the mental state, the ammonia concen- after 7 days’ treatment with L-ornithine-L-aspartate or placebo in tration and the performance time for the NCT-A. The the various subgroups (SHE = subclinical hepatic encephalopathy) (after Kircheis et al., 1997) product was predominantly well tolerated without caus- ing any serious adverse reactions. and the before/after comparison between the groups showed statistically significant differences in favour of A further multicentre, randomized double-blind trial has Placebo-controlled L-ornithine-L-aspartate (p=0.0011 and p=0.0003, also been carried out with placebo control (Feher et al., double-blind trial on respectively). 1997). In this study, 80 patients with alcohol-induced 80 patients with cirrhosis of the liver and established hyperammon- cirrhosis of the liver Safety and Infusion therapy was well tolerated by 88% of the aemia (defined as >50 µmol/l) were enrolled. Over 7 and hyperammonaemia tolerability patients in the L-ornithine-L-aspartate groups and days, the patients received either a four-hour infusion 100% of the patients given placebo. Adverse events of 20 g L-ornithine-L-aspartate in 250 ml saline solu- with shortened duration of treatment occurred in 7 tion (N=40) or physiological saline (N=40). Investiga- patients: tions were carried out after 3, 5 and 7 days. The ammonia concentration was measured in the morn- L-ornithine-L-aspartate group: ings, in the fasting state. Clinical symptoms and signs • 3 patients with gastrointestinal symptoms (nausea/ were also recorded. vomiting) • 1 patient with an acute abdomen due to a At the start of the study, mean venous ammonia con- perforated ulcer centrations were comparable, at 77 µmol/l in the • 1 patient who developed hepatorenal syndrome L-ornithine-L-aspartate group and 82 µmol/l in the pla- cebo group. During the course of treatment, the mean 90 91
  • 47. values sank by 32% (to 52 µmol/l after 7 days) on L-aspartate group and 28 in the placebo group. The Overall assessment of L-ornithine-L-aspartate and by 15% (to 70 µmol/l after 7 number of patients who showed no improvement was therapeutic success days) on placebo. On treatment with L-ornithine-L-aspar- clearly higher in the placebo group (12 vs 7). The over- tate, the mean ammonia concentration fell almost to the all assessment of tolerability showed that L-ornithine- upper limit of normal. The difference between the test L-aspartate was predominantly well or satisfactorily group and placebo was statistically significant (p<0.05). tolerated, and poorly tolerated in only 3 cases. No adverse effects were seen in either treatment group. Evaluation of relevant clinical symptoms showed a The results of this placebo-controlled trial once again decrease for all criteria in both treatment groups. Al- confirm the efficacy of Hepa-Merz® in patients with cir- though this was more pronounced in the OA group, it rhosis of the liver and raised ammonia concentrations, did not reach statistical significance because of the as well as its good tolerability increased number of cases. There was, however, a trend towards a clear reduction in the patient numbers in the L-ornithine-L-aspartate (LOLA) group in compari- 6.3.2 Meta-analysis of placebo- son with placebo (Table 6.3). controlled trials At the end of treatment, an overall assessment of ther- In the context of a meta-analysis, a quantitative system- Meta-analysis of apeutic success was made by the physician. Clinical ic overview of randomized placebo-controlled clinical randomized placebo- improvements were seen in 33 patients in the L-ornithine- trials with L-ornithine-L-aspartate infusion concentrate controlled clinical was carried out to investigate treatment effects trials with L-ornithine- LOLA LOLA Placebo Placebo before after before after (Delcker et al., 2000). The data analysis was conduct- L-aspartate infusion Fatigue 21 10 27 17 ed in accordance with the QUORUM statement on the concentrate Feeling of fullness 19 14 22 16 quality of reports for meta-analyses (Moher et al., Gastrointestinal 16 6 17 6 1999). Blinded individual data on 246 patients from five symptoms randomized controlled clinical trials formed the basis of Nausea 15 4 7 5 the evaluation. Two of these trials had already been Loss of appetite 22 11 22 13 published and biometric final reports were available for Jaundice 21 14 25 19 the other three. Foetor hepaticus 9 5 11 9 Ascites 21 20 21 18 In all five trials, patients with hepatic encephalopathy as Pruritus 4 2 7 5 a complication of cirrhosis of the liver were treated with Table 6.3: Number of patients with clinical symptoms or signs be- either L-ornithine-L-aspartate infusion concentrate or fore and after 7 days’ treatment with Hepa-Merz® or placebo (after placebo over a period of 7 days. The mental state (HE Feher et al., 1997) 92 93
  • 48. grade), the number connection test A (NCT-A) perfor- ence between treatments after 7 days was statistically mance time and the venous ammonia concentrations significant with p=0.015. were used for the analysis of efficacy. 100 L-ornithine-L-aspartate infusion With respect to the mental state of the patients, there Placebo 90 was a significant improvement on L-ornithine-L-aspar- Ammonia (µmol/l) tate in comparison with placebo after 7 days’ treatment. 80 The odds ratio was 3.22 with a 95% confidence inter- 70 val of 1.38 to 7.55 (p<0.01). 60 50 The performance time for the number connection test p < 0.015 was more clearly reduced on L-ornithine-L-aspartate 40 treatment than with placebo (Figure 6.11). The differ- Day 0 1 after 3 4 5 6 after 2 days 7 days ence between treatments after 7 days was statistically significant at p<0.001. Figure 6.12: Venous postprandial ammonia concentrations before the start of treatment (Day 0) as well as after 2 and 7 days’ treat- ment with L-ornithine-L-aspartate or placebo. Figures given are the The venous postprandial ammonia concentration also mean ± SEM, database 246 patients (after Delcker et al., 2000) showed a significantly greater reduction on L-ornithine- L-aspartate than on placebo (Figure 6.12). The differ- L-ornithine-L-aspartate was predominantly well tolerat- ed. Documented adverse effects were restricted to 80 L-ornithine-L-aspartate infusion nausea, vomiting and fatigue. Placebo 70 60 Seconds Summary: 50 In summary, this meta-analysis based on the individual data of 246 40 patients from randomized placebo-controlled clinical trials shows that 7 30 days’ treatment with Hepa-Merz® infusion concentrate leads to improve- p < 0.001 20 ment of the mental state, reduction in the time needed to complete the Day 0 1 after 3 4 5 6 after number connection test and lowering of the ammonia concentration in 2 days 7 days the blood, while generally being well tolerated. The treatment differ- Figure 6.11: Performance time for the number connection test ences in comparison to placebo were always statistically significant in (NCT-A) before the start of treatment (Day 0) as well as after 2 and favour of Hepa-Merz® infusion concentrate. 7 days’ treatment with L-ornithine-L-aspartate or placebo. Figures given are the mean ± SEM, database 246 patients (after Delcker et 94 al., 2000) 95
  • 49. 6.4 Clinical results with oral At the same time all participants were given a diet con- Hepa-Merz ® therapy taining 1 g protein/kg body weight/day in three divided meals. Examinations were carried out prior to the start of In the long-term treatment of associated conditions and treatment (day 0) and after 7 and 14 days. The main out- sequelae of diseases with impaired detoxification func- come measures were postprandial venous ammonia tion of the liver (e.g. cirrhosis), it is important that an concentration (1 hour after the morning protein meal) and effective oral form of the medicinal product is also avail- the performance time for the NCT-A carried out at the able. L-ornithine-L-aspartate can be used long-term in same time. Further parameters of efficacy included the the form of Hepa-Merz® Granules 6000 (1 sachet with mental state (HE grade), the PSE index and the venous 10 g granules contains 6 g L-ornithine-L-aspartate) or ammonia concentrations under fasting conditions. Hepa-Merz® Granules 3000 (1 sachet with 5 g granules contains 3 g L-ornithine-L-aspartate). The efficacy of The results of venous postprandial ammonia concen- this pharmaceutical form has also been studied in clini- tration showed statistically significant differences in cal trials. favour of L-ornithine-L-aspartate in both the before/ after comparison and in the group comparison (Figure 6.13). 6.4.1 Hepa-Merz ® Granules in Posprandial ammonia level measured (µmol/l) comparison with placebo 180 ** 160 Placebo-controlled The efficacy of L-ornithine-L-aspartate granules com- 140 double-blind trial pared with placebo was tested in a multicentre ** 120 in 66 patients with randomized double-blind trial in 66 patients with cirrhosis 100 cirrhosis of the liver of the liver and stable chronic overt (HE grade I/II) or 80 and HE grade 0 subclinical hepatic encephalopathy (HE grade 0) 60 (subclinical) to II (Stauch et al., 1998). Further inclusion criteria were 40 hyperammonaemia (fasting venous ammonia concen- 20 **p < 0.01 0 tration >50 µmol/l) and a performance time >30 s in the 0 7 14 0 7 14 number connection test (NCT-A). Duration of treatment (in days) The patients were given 2 sachets of Hepa-Merz® Mean ± SD OA (P25 to P75) Granules 3000 (each containing 3 g L-ornithine- Median Placebo (P25 to P75) L-aspartate) dissolved in water, three times a day (total Figure 6.13: Effects of L-ornithine-L-aspartate (left) and placebo (right) daily dose: 18 g) for 14 days (N = 34) or a correspond- on the postprandial venous ammonia concentration. Figures given are ing placebo (N = 32). the mean (black square) and standard deviation, median (white square), 25th and 75th percentiles (after Stauch et al., 1998) 96 97
  • 50. A similar result was seen in the venous ammonia con- change was seen with placebo (1.16 ± 0.65 vs 0.93 ± centrations measured under fasting conditions. Here 0.63, p>0.05). the group difference was clearly in favour of L-ornithine- L-aspartate. With the baseline clinical assessment of HE 0, a reduc- tion in the NCT-A performance time to <30 seconds With respect to the second main outcome measure, the was taken as evidence of improvement. The clinical performance time for the NCT-A, there was a statisti- relevance of the treatment difference between L-ornithine- cally significant group difference in favour of L-ornithine- L-aspartate and placebo is particularly obvious when L-aspartate after 14 days (p<0.05). While the time considering the number and proportion of patients with required for the test stayed more or less constant in the improvement of the HE grade. More than twice as many placebo group, it was progressively shortened on treat- patients improved on L-ornithine-L-aspartate as did on ment with L-ornithine-L-aspartate (Figure 6.14). placebo. 120 Calculation of the modified PSE index included the HE ** 100 ** grade, the postprandial venous ammonia concentration and the NCT performance time. In accordance with the 80 NCT-A (sec) statistically significant group differences in favour of 60 L-ornithine-L-aspartate found in these three parame- 40 ters, the difference in the PSE index was also statisti- 20 cally significant at p<0.01. The mean PSE index in the **p < 0.01 0 L-ornithine-L-aspartate group was 0.29 ± 0.11 at the 0 7 14 0 7 14 start of treatment, improving to 0.20 ± 0.14 after 14 Duration of treatment (in days) days (p<0.01). The corresponding values for the place- Mean ± SD OA (P25 to P75) bo group were 0.32 ± 0.12 vs 0.28 ± 0.15 (n.s.). Median Placebo (P25 to P75) Figure 6.14: Effects of L-ornithine-L-aspartate (left) and placebo Treatment was predominantly well tolerated in both (right) on performance time in the number connection test. Figures groups (L-ornithine-L-aspartate 94% and placebo given are the mean (black square) and standard deviation, median (white square), 25th and 75th percentiles (after Stauch et al., 1998) 81%). Two patients in the L-ornithine-L-aspartate group and 6 patients in the placebo group rated the tolerabili- The HE grade established clinically showed a statisti- ty as moderate. No patients showed any adverse reac- cally significant improvement, from a mean of 1.04 ± tions to the medication. One patient in each group was 0.54 to 0.68 ± 0.47, after 14 days’ treatment with excluded from the trial prematurely because of poor L-ornithine-L-aspartate (p<0.05) while no significant compliance. 98 99
  • 51. One further patient on placebo had to be switched to hol misuse (71%); viral infections, medicines, industrial another therapy because of worsening encephalopathy. chemicals and other aetiological factors were also men- tioned. The most frequent diagnosis was that of fatty liver (55.5%), followed by cirrhosis of the liver (32.4%) Summary: and chronic hepatitis (21.7%). Other diagnoses were of These placebo-controlled clinical trials show that the oral form of L-orni- lesser importance (multiple entries were possible). thine-L-aspartate is comparable to L-ornithine-L-aspartate infusion con- centrate with respect to efficacy and tolerability. It was planned that parameters routinely used by the Laboratory tests physician to monitor the course of the disease – aspar- for therapeutic tate aminotransferase (AST), alanine amino-transferase monitoring (ALT), gamma-glutamyl transferase (γ−GT), bilirubin and 6.4.2 Hepa-Merz ® Granules in the the prothrombin time – would be measured before and medical practice after treatment. Evaluation of these parameters showed clear reductions in the mean values of AST, ALT, γ−GT Observation of use In order to study the effectiveness and tolerability of and bilirubin with a slight increase in the prothrombin in 1167 patients treatment with L-ornithine-L-aspartate granules under time over the entire patient population. Figure 6.15 with liver diseases conditions of medical practice, observation of use was gives an overview of the three largest diagnostic groups carried out in 250 internal and general medical prac- – patients with fatty liver, cirrhosis of the liver and chron- tices (Grüngreiff and Lambert-Baumann, 2001). ic hepatitis – and the most frequently measured param- Records were kept on patients with chronic liver dis- eters AST, ALT and γ−GT. eases who had previously been unsuccessfully treated with general non-pharmacological measures and in The results show very clearly that there was a reduction whom the physician saw an indication for medication in the clinically relevant parameters in all three diagnos- with L-ornithine-L-aspartate granules. Besides the tic groups, most pronounced in patients with fatty liver. usual medical history, data concerning diagnosis, dos- Patients were also subdivided into three groups with age and duration of treatment, therapeutic monitoring respect to the daily dose (normal dose 9 g L-ornithine- (clinical symptoms and routine laboratory tests) and L-aspartate/day, <9 g OA/day and >9 g OA/day) and to tolerability were documented. In total, data were collect- the duration of therapy (<30 days, 31-60 days, 61-90 ed on 1167 patients. The mean age of these patients days) in order to investigate the relationship of these cri- was 53.5 years (18 to 87 years) and the majority were teria to the therapeutic effects. There was a positive men (71%). On average, the liver disease had been relationship between the percentage reduction in the known about for some 4-5 years. The underlying cause liver enzymes and the daily dosage and duration of most frequently suspected by the physician was alco- treatment. 100 101
  • 52. % The clinical symptom of “fatigue” which was recorded 20 also showed a clear improvement during the course of treatment. In 178 of the patients with cirrhosis of the Percentage reduction in transaminases 10 liver, very marked fatigue was recorded initially; this 0 before and after treatment improved in 95% of the patients. The mild to moderate -10 fatigue experienced by 157 patients at the start of treat- -20 ment was no longer present in 53% of these patients at -30 the final assessment, as can be seen in Figure 6.16. -40 At the end of the observation period, the treating physi- Overall assessment -50 cians made an overall assessment of the effectiveness of efficacy and and tolerability of treatment with L-ornithine-L-aspartate. tolerability -60 AST ALT γ-GT Analysis of these data showed their positive assess- -70 n = 963 cirrhosis ment of treatment success (Figure 6.17). fatty liver chr. hep. Improvement in HE/fatigue in patients with cirrhosis Figure 6.15: Changes in AST, ALT and γ−GT on treatment with Hepa- 180 Merz® Granules in the three largest diagnostic groups. Data on patient numbers (N) and percentage decrease in transaminases (after 160 Grüngreiff and Lambert-Baumann, 2001) 140 Number of patients 120 Additional factors which had positive effects on the 100 levels of the liver enzymes were good compliance and 80 a definite abstinence from alcohol during the period of 60 Improvement in observation. In 348 of the patients with cirrhosis, infor- 40 clinical symptoms mation was supplied on hepatic encephalopathy (HE). 20 on L-ornithine- In 105 (30%) of these patients mild (HE grade I) and in 0 L-aspartate 27 (8%) moderate (grade II) hepatic encephalopathy HE I HE II severe mild was initially diagnosed. Analysis showed that 78% of fatigue fatigue the patients with moderate hepatic encephalopathy n = 348 before treatment improved to a lower grade and 49% of the patients after treatment with grade I hepatic encephalopathy regressed to grade 0. Figure 6.16: Effects of treatment with Hepa-Merz® Granules on the clinical parameter “fatigue” (after Grüngreiff and Lambert-Baumann, 2001) 102 103
  • 53. And in only 8 cases did the physician consider that 6.4.3 Hepa-Merz® Granules in there was a possible or probable causal relationship comparison with lactulose between L-ornithine-L-aspartate and adverse events. These were mild and mainly gastrointestinal symptoms. The disaccharide lactulose – which is not cleaved in the Controlled clinical There were no serious adverse drug reactions. gastrointestinal tract – has been used for a long time in studies in patients the treatment of hepatic encephalopathy (see section with cirrhosis Therapeutic Tolerability 4.3). However, the therapeutic use of lactulose is limited efficacy because of its frequently occurring adverse effects (gastrointestinal symptoms, diarrhoea). Because the mechanisms of action of L-ornithine-L-aspartate and lactulose are basically different, a direct comparison of the efficacy and tolerability of the two substances seemed to be clinically relevant. very good very good good good To this end, a monocentre randomized clinical trial in moderate/slight moderate/slight parallel groups was carried out (Liehr et al., 1992; none Kircheis et al., 1993; Krüger et al., 1994) in which 48 Figure 6.17: Overall assessment of the efficacy (left) and tolerability patients with cirrhosis of the liver, hyperammonaemia (right) of treatment with Hepa-Merz® Granules at the end of treatment, (>50 µmol/l) and minimal or overt hepatic encephalop- shown as percentages (after Grüngreiff and Lambert-Baumann, 2001) athy were included. The patients were treated for 14 days with either L-ornithine-L-aspartate granules (3 x Summary: 9 g per day) or lactulose (initial dose 3 x 33 g, followed The results of this observation of use in 1167 patients with chronic liver by individual adjustment of the daily dose). Both groups disease substantially confirm the efficacy and the good tolerability of showed a reduction in the mean NCT performance Hepa-Merz® Granules shown in controlled clinical trials, under conditions time: from 58 s to 47 s in the L-ornithine-L-aspartate pertaining to the medical practice. groups and from 66 s to 53 s in the lactulose group. The mean ammonia concentration was lowered only on L-ornithine-L-aspartate (from 120 µmol/l to 105 µmol/l). Mean values of γ−GT improved in both groups. HE grading also improved in both groups, whereby 29% of patients on L-ornithine-L-aspartate no longer had any discernable HE at the end of treatment compared with only 5% of lactulose patients. Treatment with L-ornithine- 104 105
  • 54. L-aspartate was much better tolerated than lactulose of therapeutic use and clinical studies in patients with mild therapy. 45% of the patients treated with lactulose to severe impairment of hepatic function. The majority reported adverse reactions, mostly diarrhoea commenc- were patients with cirrhosis but patients with other liver ing within the first three days. diseases were also treated. The documented duration of treatment ranged from a few days to several years. 6.5 Summary of results with Hepa-Merz ® Recent placebo-controlled double-blind trials with L-ornithine-L-aspartate infusion concentrate and Effects of L-ornithine- Pharmacodynamic effects and dose-effect relationships L-ornithine-L-aspartate granules have been carried out L-aspartate were investigated in experimental clinical studies with in accordance with the current requirements of evidence- L-ornithine-L-aspartate. It has been shown that treat- based medicine. With respect to its efficacy in cirrhosis ment with L-ornithine-L-aspartate: of the liver and hepatic encephalopathy (subclinical to HE grade II), average and clinically relevant findings on • lowers the elevated ammonia concentration in the treatment with L-ornithine-L-aspartate in comparison blood and increases the formation of urea with placebo show that: • reduces or prevents pathological postprandial • the mental state improves (significant reduction in the ammonia levels in the blood HE grade) • counteracts amino acid imbalance (increase of the • the PSE index falls significantly BCAA/AAA ratio) • performance time in the number connection test is • improves protein synthesis in the muscle significantly reduced (evidence of anti-catabolic action) • ammonia concentrations in the fasting and postpran- • stabilized psychometric functions and the mental dial states are significantly lowered. state under protein loading • reduces pathological glutamine and glutamate The results of experimental clinical studies, many obser- concentrations in the brain in parallel with the vations of therapeutic use and clinical trials with L-orni- lowering of ammonia in the arterial blood thine-L-aspartate have thus been confirmed in accor- • has dose-dependent effects. dance with the criteria of evidence-based medicine. The tolerability of L-ornithine-L-aspartate was good; Efficacy and The results of experimental clinical studies are in agree- serious adverse reactions did not occur. In a few cases, tolerability of ment with the findings of experimental animal studies. The patients receiving L-ornithine-L-aspartate infusion ther- L-ornithine- clinical efficacy and tolerability of L-ornithine-L-aspartate apy experienced mild gastrointestinal symptoms which L-aspartate as an infusion, with oral administration or a combination could be interpreted as evidence of adverse drug reac- of the two, have been investigated in many observations tions to L-ornithine-L-aspartate. 106 107
  • 55. 7 SAFETY AND TOLERABILITY Data on safety and tolerability of Hepa-Merz® from the With severely impaired hepatic function, the infusion observations of therapeutic use, clinical studies and should be reduced to a rate that the individual can toler- especially the placebo-controlled double-blind trials ate. have proven that the tolerability of L-ornithine-L-aspar- tate is very good. There were no cases of serious ad- Because of its mechanism of action, L-ornithine- Attention to renal verse drug reactions. L-aspartate leads to the increased formation of urea function (creatinine which has to be eliminated via the kidneys. L-ornithine- not greater than In the placebo-controlled double-blind trials with large L-aspartate should therefore not be used in cases 3 mg/dl) case numbers, there were three cases (5% of the where there is severe impairment of renal function. As a L-ornithine-L-aspartate treated patients) of mild gastro- general rule, the creatinine level should not be greater intestinal disturbances i.e. nausea/vomiting with infu- than 3 mg/dl. sion therapy (Kircheis et al., 1997); there were no cases in the placebo group. In the largest placebo-controlled trial with L-ornithine-L-aspartate granules, there were no adverse events at all in either group (Stauch et al., 1998). It is known from spontaneous notification of suspected adverse drug reactions and reports from therapeutic practice that nausea occasionally occurs on infusion therapy, with vomiting rarely. The symptoms are gener- ally transient and are reversible with a reduction in the dose or the rate of infusion. Rate of infusion In summary it can be said that L-ornithine-L-aspartate should not be greater therapy is generally very well tolerated and that adverse than 5 g L-ornithine- reactions may occur rarely, in the form of mild gastroin- L-aspartate per hour testinal disturbances. To prevent such reactions, a maximum infusion rate of 5 g L-ornithine-L-aspartate infusion concentrate per hour is recommended. 108 109
  • 56. 8 CHEMISTRY, TOXICOLOGY AND PHARMACOKINETICS OF HEPA-MERZ ® 8.1 Chemico-physical data 8.2 Toxicology Toxicological tests of L-ornithine-L-aspartate on rats Chemical name (S) - 2,5 – diaminopentanoic acid – (S) 2 amino succinate and dogs following single doses and after repeated INN L-ornithine-L-aspartate administration of infusions over 4 weeks gave a no- Structural formula H NH3 effect level of approx. 1500 mg/kg. O C C CH2 CH2 CH2 NH3 O C CH2 C C O O NH3 O H O Reproduction studies on mutagenicity found no abnor- Molecular formula C 9 H19 N3 O6 malities. There is no need to suspect any carcinogenic Molecular weight 265.3 potential. Appearance white or colourless crystalline powder Odour odourless Taste metallic, salty 8.3 Pharmacokinetics Solubility readily soluble in water, poorly soluble in ethyl alcohol L-ornithine-L-aspartate is rapidly absorbed and cleav- ed into L-ornithine and L-aspartate. The elimination L-ornithine-L-aspartate, the stable salt of the naturally- half-life of each the amino acids is short – approx. 40 occurring amino acids, L-ornithine and L-aspartic acid, minutes. Some L-aspartate also appears unchanged in is available in the pharmaceutical forms of granules, the urine. chewable tablets and infusion concentrate. 1 sachet of Hepa-Merz® Granules 3000 contains 3.0 g of L-ornithine- The bioavailability is 82.2 ± 28% after either intrave- L-aspartate; 1 sachet of Hepa-Merz® Granules 6000 nous or oral administration. contains 6.0 g of L-ornithine-L-aspartate. Hepa-Merz® Chewable tablets, containing 3.0 g L-ornithine- L-aspartate, have the great advantage that no water or other fluid is required to take them. Their pleasant fruit flavour aids patient compliance. 10 ml infusion con- centrate contain 5.0 g L-ornithine-L-aspartate in water for injection. 110 111
  • 57. 9 BASIC INFORMATION Hepa-Merz ® Granules Contraindications Severe impairment of kidney function (renal failure) Active substance Serum creatinine should not be greater than 3 mg/100ml. L-ornithine-L-aspartate Use in pregnancy and lactation: Composition Ornithine-aspartate has no known damaging effects 1 sachet with 5 g granules contains during pregnancy and lactation. Contains fructose. Active ingredients When taken according to the dosage recommenda- L-ornithine-L-aspartate 3.0 g tions, each dose of the granules supplies 1.13 g fruc- tose per sachet. Due to the possibility of hitherto unde- Other ingredients tected fructose intolerance, this medicinal product Citric acid, anhydrous should only be given to babies and young children after Saccharin sodium consultation with the treating physician. It is absolutely Sodium cyclamate essential that adolescents and adult patients with he- Fructose reditary fructose intolerance consult the treating physi- Povidone cian before taking this medicinal product. Flavourings E 110 colouring Adverse reactions None known Note for people with diabetes 1 sachet with granules contains 1.13 g fructose Warnings (corresponding to 0.11 carbohydrate exchanges) This medicine contains the colouring agent E 110 (Sun- set yellow) which may cause allergic reactions – includ- Indications ing asthma – in people who are particularly sensitive Treatment of associated conditions and sequelae of to this substance. Allergy is seen more frequently in diseases with impaired hepatic detoxification (e.g. people who are allergic to acetyl salicylic acid. cirrhosis of the liver), when there are symptoms and signs of minimal or overt hepatic encephalopathy. 112 113
  • 58. Mode of action Hepa-Merz ® Infusion concentrate Hepa-Merz® contains L-ornithine-L-aspartate, which stimulates ammonia detoxification by increasing urea Active substance synthesis in the urea cycle. In addition it detoxifies the L-ornithine-L-aspartate extrahepatic ammonia in the tissues. Composition Dosage 1 ampoule with 10 ml contains Take the contents of 1-2 sachets Hepa-Merz® Granules dissolved in water, up to three times a day Active ingredients L-ornithine-L-aspartate 5.0 g Interactions with other medicines None known Other ingredients Water for injection Indications Treatment of associated conditions and sequelae of diseases with impaired hepatic detoxification (e.g. cir- rhosis of the liver), when there are symptoms and signs of minimal or overt hepatic encephalopathy; especially for the treatment of incipient loss of consciousness (pre-coma) and clouding of consciousness (coma) Contraindications Severe impairment of kidney function (renal failure). Serum creatinine should not be greater than 3 mg/100ml. Use in pregnancy and lactation Ornithine-aspartate has no known damaging effects during pregnancy and lactation. Adverse reactions Occasionally nausea has been reported and rarely vomiting. However these are usually transient and do 114 115
  • 59. 10 ABBREVIATIONS not require discontinuation of the medicinal product: AAA Aromatic amino acids they disappear with reduction in the dose or the rate of ALF Acute liver failure infusion. ALT Alanine aminotransferase AP Alkaline phosphatase Warnings AST Aspartate aminotransferase None BCAA branched-chain amino acids BUI Brain uptake index Mode of action CAH Chronic active hepatitis Stimulation of ammonia detoxification by increasing CC Clinical control group urea synthesis in the urea cycle. Extrahepatic detoxifi- CFF Critical flicker frequency cation of ammonia in the tissues. CHE Cholinesterase ChT Chewable tablet Dosage cps Cycles per second As long as not otherwise prescribed, up to 4 ampoules CRT Choice reaction time daily. With incipient loss of consciousness (pre-coma CT Computerised tomography and clouding of consciousness (coma) up to 8 am- Cr Creatinine poules within 24 hours, depending on the severity of the dl Decilitre condition. DST Digit symbol test EEG Electroencephalogram Interactions with other medicines Fig Figure None known GABA Gamma aminobutyric acid GCP Good clinical practice GOT Glutamic-oxaloacetic transaminase GDH Glutamate dehydrogenase Gln Glutamine Glu Glutamate GPT Glutamic-pyruvic transaminase γ-GT Gamma-glutamyl transferase HE Hepatic encephalopathy INR International normalised ratio (= thromboplastin time) l Litre LD Lethal dose LTT Line tracing test 116 117
  • 60. 11 REFERENCES MRI Magnetic resonance imaging 11.1 General references MRS Magnetic resonance spectroscopy µmol Micromol Blei AT, Butterworth RF (Eds.). Hepatic Encephalopathy. mg Milligram Seminars in Liver Disease 1996; Vol. 16, No. 3, Thieme, N Number New York, Stuttgart. NASH Non-alcoholic steatohepatitis NCT Number connection test Blei AT. Diagnosis and treatment of hepatic encephalop- NH3/NH4+ Ammonia/ammonium ion athy. Bailliere's Clinical Gastroenterology 2000; 14(6): NMR Nuclear magnetic resonance 959–974. n.s. not significant OA L-ornithine-L-aspartate Böker K, Heringlake S. Das akute Leberversagen. Kli- PSE Portosystemic encephalopathy nikarzt 1999; 2/28: 54–58. QUORUM Quality of reporting of meta-analysis s Seconds Conn HO, Bircher J (Eds.). Hepatic Encephalopathy: SD Standard deviation Syndromes and Therapies. Medi-Ed Press 1994, Bloo- SEM Standard error of the mean mington, Illinois. SHE Subacute hepatic encephalopathy Tab Table Caspary W.F Hepatische Enzephalopathie. In: Caspary TIPS Transjugular intrahepatic portosystemic W.F, Leuschner U, Zeuzem S. (Hrsg.). Therapie von stent shunt Leber- und Gallekrankheiten. 2. Aufl., Springer-Verlag, VEP Visual evoked potential 2001: 309–325. Ferenci P, Müller C. Hepatic encephalopathy: treatment. In: McDonald JWD, Burroughs AK, Feagan BG (Eds.). Evidence based gastroenterology and hepatology. BMJ Books 1999, London; 443–455. Gerber T, Schomerus H. Hepatic encephalopathy in liver cirrhosis, pathogenesis, diagnosis and manage- ment. Drugs 2000; 60(6): 1353–1370. Gerok W, Blum H.E. (Hrsg). Hepatologie. Urban & Schwarzenberg 1995, München. 118 119
  • 61. Häussinger D, Kircheis G, Fischer R, Schliess F, vom Trautwein C, Manns MP. Chronische Hepatitis. Der Dahl S. Hepatic encephalopathy in chronic liver dis- Internist 1997; 3: 283–295. ease: a clinical manifestation of astrocyte swelling and low-grade cerebral edema? Journal of Hepatology Mullen K.D, Dasarathy S. Hepatic Encephalopathy. In: 2000; 32: 1035–1038. Schiff E.R, Sorrell M.F, Daddrey W.C (Editors). Diseases of the Liver, Lippincott Williams & Wilkins Philadelphia 1999. Häussinger D, Maier KP. Hepatische Enzephalopathie. Georg Thieme Verlag 1996, Stuttgart, New York. Wein Ch, Popp B, Koch H. Neuropsychologische Untersuchungen und Fahrverhalten bei Patienten mit Häussinger D. Nitrogen metabolism in liver: structural Leberzirrhose, Neurol. Rehabil. 2001; 7(5): 242–262. and functional organization and phy-siological rele- vance. Biochem. J. 1990; 267: 281–290. Weißenborn K. Hepatische Enzephalopathie. In: Schmidt E., Schmidt FW, Manns MP (Hrsg.). Leberer- Kaiser S, Gerok W, Häussinger D. Ammonia and gluta- krankungen: Pathophysiologie-Diagnostik-Therapie, mine metabolism in human liver slices: new aspects on Wiss. Verl.Ges. Stuttgart, 2000; ISBN 3-8047-1640-7. the pathogenesis of hyperammonaemia in chronic liver disease. Eur. J. Clin. Invest. 1988; 18(5): 535–542. 11.2 References on Hepa-Merz ® Kircheis G, Wettstein M, Timmermann L, Schnitzler A, Häussinger D. Critical flicker frequency for quantification Albrecht J, Hilgier W, Januszewski S, Kapuscinski A, of low-grade hepatic encephalopathy. Hepatology Quack G. Increase of the brain uptake index for 2002; 35: 357–366. L-ornithine in rats with hepatic encephalopathy. Neuro- report 1994; 5: 671–673. Kramer L, Tribl B, Gendo A, Zauner C, Schneider B, Ferenci P, Madl C. Partial pressure of ammonia versus Albrecht J, Hilgier W, Januszewski S, Quack G. Contra- ammonia in hepatic encephalopathy. Hepatology 2000; sting effects of toxic liver damage on the brain uptake 31(1): 30–34. indices ornithine, arginine and lysine: modulation by treatment with ornithine aspartate. Metabolic Brain Kuhlbusch R, Enck P, Häussinger D. Hepatische Enze- Diseases 1996; 11: 229–237. phalopathie: neuropsychologische und neurophysiolo- gische Diagnostik. Z. Gastroenterol. 1998; 36: 1075– Aschke J. Erfahrungen mit L-Ornithin-L-Aspartat bei 1083. Leberkranken. Med. Welt 1969, 20(12): 657–662. 120 121
  • 62. Baumann M. Klinische Erfahrungen mit Hepa-Merz. Grossi CE, Prytz B, Rousselot LM. Amino acids mix- Zeitschrift Allgemeinmed. 1970; 46(17): 895–900. tures in prevention of acute ammonia intoxication in dogs. Arch Surg 1967; 94: 261–266. Delcker A, Jalan R, Schumacher M, Comes G. L-orni- thine-L-aspartate vs placebo in the treatment of hepat- Grüngreiff K, Lambert-Baumann J. Wirksamkeit von ic encephalopathy: A meta-analysis of randomized pla- L-Ornithin-L-Aspartat-Granulat bei chronischen Leber- cebo-controlled trials using individual data. Hepatol erkrankungen. Ergebnisse einer Anwendungsbeobach- 2000; 32(4), Pt. 2 of 2, 310 A (Abstract 604). tung bei 1167 Patienten. Med Welt 2001; 52: 219–226. Delcker A, Turowski B, Mihm U, Raab P., Rusch O, Pila- Handschuh H. Ammoniaksenkung als Ziel. Fortschr tus U, Zanella F.E, Proton MR Spectroscopy of Neuro- Med 1990; 108(13): 83. metabolites in Hepatic Encephalopathy During L-Orni- thine-L-Aspartate Treatment – Results of a Pilot Study. Hendricks R, Hellweg H-R. Therapie von Lebererkran- Metabolic Brain Disease 2002, Vol. 17, No. 2 (in press). kungen mit oral verabreichtem Ornithin-aspartat – Ver- laufsbeobachtung über 6 Monate. Med. Welt 1984; 35: Fehér J, Láng I, Gógl A et al. Effect of ornithine-aspar- 596–600. tate infusion on elevated serum ammonia concentration in cirrhotic patients - results of a randomized, placebo- Henglein-Ottermann D, Der Einfluß von Ornithin-Aspar- controlled double-blind multicentre trial. Med Sci Monit tat auf die experimentell erzeugte Hyperammoniämie. 1997; 3(5): 669–673. Klinisch-experimentelle Studie. Therapie der Gegenwart 1976; 115: 9. Gebhardt R, Beckers G, Gaunitz F et al. Treatment of cirrhotic rats with L-ornithine-L-aspartate enhances Hermann G. Experimentell erzeugte endogene Hyper- urea synthesis and lowers serum ammonia levels. ammoniämien durch Narkotika an der Ratte und deren J Pharmacol Exp Ther 1997; 283(1): 1–6. Beinflussung durch L-Ornithin-L-Aspartat. in: Ed. Szam. Ammoniakstoffwechsel. Schattauer Verlag, Greenstein JP, Winitz M, Gullino P et al. Studies on the Stuttgart-New York 1972; 219–223. metabolism of amino acids and related compounds in vivo. III. Prevention of ammonia toxicity by arginine and Hunold W. Klinische Erfahrungen bei Hepatopathien – related compounds. Arch Biochem 1956; 64: 342–254. insbesondere bei Patienten mit alko-holtoxisch und nutritivtoxisch bedingter Fettleber – unter der Monothe- rapie mit Ornithin-aspartat. Z für Allgemeinmedizin 1973; 10 (49. Jahrg.): 469–472. 122 123
  • 63. Kalk H. Die Klinik der akuten Leberinsuffizienz. Liehr M, Huth M, Kircheis G, Wagner M. A comparison Gastroenterologia 1958, 90: 217–290. of l-ornithine-l-aspartate and lactulose in the manage- ment of chronic liver disease and hepatic encephalopa- Kircheis G, Nilius R, Held C et al. Therapeutic efficacy of thy. J Gastroenterol Hepatol 1992; 7 (suppl1): abstract L-ornithine-L-aspartate infusions in patients with cirrho- 106. sis and hepatic encephalopathy: results of a placebo- controlled, double-blind study. Hepatology 1997; 25(6): Melzer H, Weber D, Wotzka R. Zur Therapie von Leber- 1351–1360. krankheiten mit L-Ornithin-L-Aspartat. Med. Klinik 1969; 64(35): 1541–1544. Kircheis G, Quack G, Erbler H. L-ornithine-L-aspartate in the treatment of hyperammonemia and hepatic en- Müller-Kengelbach P. Behandlung chronischer Leber- cephalopathy. in: Eds. Conn HO, Bircher J. Hepatic schäden mit Ornithin-aspartat. Therapie Woche 1986; Encephalopathy: Syn-dromes and Therapies. Medi-ED 36: 3743–3749. Press, Bloomington, Illinois 1993: 373–383. Müting D, Kalk J-F, Fischer R, Wurzel H, Reikowski J. Kosozu K. Clinical study on the effects of L-ornithine- Hepatic detoxification and hepatic function in chronic L-aspartate on liver dysfunction. [Article in Japanese]. active hepatitis with and without cirrhosis. Digestive Iryo 1966; 20(4): 339–346. Diseases and Sciences 1988; 33 (1): 41–46. Krüger B, Held C, Kircheis G. Ornithinaspartat bei hepa- Müting D, Kalk JF, Klein CP. Long-term effectiveness of tischer Enzephalopathie : ein alter neuer Therapieansatz. high-dosed ornithine-aspartate on urea synthesis rate Z. Ärztl.Fortbild (Jena). 1994; 88(9): 673–679. and portal hypertension in human liver cirrhosis. Amino Acids 1992; 3: 147–153. Leonhardt H, Bungert HJ. Therapie der schweren Hyper- ammoniämie. Med. Klinik 1972; 32/33: 1052–1056. Müting D, Reikowski J. Controlled study of the effect of an orally administered ammonia-lowering amino acid Leweling H, Kortsik C, Gladisch R, Staedt U, Hagmüller (ornithine-aspartate) on liver and pancreas function in E, Holm E. Effects of ornithine aspartate on plasma liver cirrhosis patients. Therapiewoche 1980; 30: ammonia and plasma amino acids in patients with liver 5990–5996. cirrhosis. A double-blind, randomized study using a four-fold crossover design. Podymova SD, Nadinskaya MJ. The treatment of hepat- In: Bengtsson F: Hepatic Encephalopathy and Metabol- ic encephalopathy. Digestion 1998; 59 [Suppl. 3]: 348. ic Nitrogen Exchange. CRC Press 1991, 377–389. 124 125
  • 64. Rees CJ, Oppong K, Mardinie H Al, Hudson M, Salvatore F, Scoppa P, Cozzolino. Protective effect of Record CO. Effect of L-ornithine-L-asparate on patients ornithine and aspartic acid in chronic carbon tetrachlo- with and without TIPS undergoing glutamine challenge: ride intoxication. Clin. Chim. Acta 1959; 4: 728–732. a double blind, placebo controlled trial. Gut 2000; 47: 571–574. Schäfer W. Die intravenöse Zufuhr von L-Ornithin- L-Aspartat bei Leberkrankheiten. Münch. Med. Wschr. Reynolds N, Downie S, Smith K, Kircheis G, Rennie MJ. 1968, 43: 2521–2525. Treatment with L-ornithine-L-aspartate (LOLA) infusion restores muscle protein synthesis responsiveness to Schmidt L. Behandlung alkoholinduzierter Hepatopa- feeding in patients with cirrhosis. Journal of Hepatology thien. Therapie der Gegenwart 1974; 11 (113. Jahrg.): 1999, (Suppl. 1) Vol. 30. 1940–1972. Rose C, Michalak A, Pannunzio P et al. L-ornithine- Schmitt W und Ziegler KB: Der Einfluss von L-Ornithin- L-aspartate in experimental portal-systemic encephalop- L-Aspartat auf den arteriellen und venösen Blutammo- athy: Therapeutic efficacy and mechanism of action. niakspiegel bei Leberzirrhotikern. Med. Welt 1970, 21: Metabolic Brain Disease 1998; 13(2): 147–157. 1361. Rose C, Michalak A, Rao KV, Quack G, Kircheis G, But- Shioya, Kuraiski K, Kakimoto M, Tamama Y. Pharma- terworth RF. L-ornithine-L-aspartate lowers plasma and cological study on L-ornithine-L-aspartate. Jap J Phar- cerebrospinal fluid ammonia and prevents brain edema macol 1964; 14: 201–214. in rats with acute liver failure. Hepatology 1999; 30(3): 636–640. Slotboom J, Vogels BAPM, De Haan JG et al. Proton resonance spectroscopy study of the effects of L-ornithi- Salvatore F, Bocchini V. Prevention of ammonia toxicity ne-L-aspartate on the development of encephalopathy, by amino acids concerned in the biosynthesis of urea. using localization pulses with reduced specific absorption Nature 1961; 191: 705–706. rate. J Magnetic Resonance 1994; B105: 147–156. Salvatore F, Cimino F, D'Ayella-Caracciolo M, Cittadini Staedt U, Leweling H, Gladisch R, Kortsik C, Hagmuller D. Mechanism of the protection by L-ornithine-L-aspar- E, Holm E. Effects of ornithine aspartate on plasma tate mixture and by L-arginine in ammonia intoxication. ammonia and plasma amino acids in patients with cir- Arch Biochem Bio-phys 1964; 107: 499–503. rhosis. A double-blind, randomized study using a four- fold crossover design. J Hepatol 1993; 19(3): 424-430. 126 127
  • 65. Stauch S, Kircheis G, Adler G et al. Orale L-Ornithin- Zieve L, Lyftogt C, Raphael D. Ammonia toxicity: com- L-Aspartat-Therapie der chronischen hepatischen parative protective effect of various arginine and orni- Enzephalopathie: Ergebnisse einer Placebo-kontrollier- thine derivatives, aspartate, benzoate, and carbamyl ten Doppelblind-Studie. J Hepatol 1998; 28: 856–864. glutamate. Metabolic Brain Disease 1986; 1: 25–35. Turowski B, Delcker A, Zanella FE. Proton-MR-Spectros- copy of neurometabolites in hepatic encephalopathy. Journal of Imaging 2001; 11(1) Nr. 4 (Abstract). Vogels BAPM, Slotboom J, de Haan JG, Bovee WMMJ, Quack G, Chamuleau RAFM. The effect of L-ornithine- L-aspartate on mild encephalopathy due to portosystem- ic shunting and hyperammonemia. In: Capocaccia L et al., eds. Advances in Hepatic Encephalopathy and Metabolic Nitrogen Exchange. CRC Press London 1995, 423–431. Vogels BA, Karlsen OT, Mass MA, Bovee WM, Chamu- leau RA. L-ornithine vs. L-ornithine-L-aspartate as a treatment for hyperammonemia-induced encephalopa- thy in rats. J Hepatol 1997; 26(1): 174–182. Vorberg G. Ambulante Behandlung Leberkranker mit Ornithinasparthat. Ärztliche Praxis 1969; 59 (21. Jahrg.): 3208. Wotzka R, Weber D. Weitere klinische Erfahrungen mit L-Ornithin-L-Aspartat bei Lebererkrankungen. Ther. Gegenwart 1972; 111: 400–412. Zicha K, Zicha M. Die Leberschutzwirkung von L-Ornithin-L-Aspartat bei Arzneimittelschäden an Rat- ten. Zeitschrift für Gastroenterologie 1968; 6: 423–429. 128 129
  • 66. Notes Notes 130 131
  • 67. Merz Pharmaceuticals GmbH Medical Sciences Eckenheimer Landstrasse 100 D-60318 Frankfurt am Main Tel: +49 (0)69.15 03-1 Fax: +49 (0)69.15 03-4 06