Pharmacology Lecture Slides on Therapy of Gout by Sanjaya Mani Dixit Assistant Professor of Pharmacology at Kathmandu Medical College

1. Therapy of Gout
Sanjaya Mani Dixit
Assistant Prof of Pharmacology

2. Metatarso-phalangeal joint of great toe
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3. Gout
• Gout is a kind of arthritis that occurs when uric acid builds up in blood
and causes joint inflammation owing to the presence of MSU crystals in
the joint and periarticular tissues.
• Acute gout is a painful condition that typically affects one joint
(Metatarso-phalangeal joint).
• Chronic gout is repeated episodes of pain and inflammation, which may
involve more than one joint.
• Causes:
– Uric acid over production (10%)
– Diminished renal clearance (90%)
Normal Serum Uric Acid Values
• Male: 3- 8 mg/dl
• Female: 2-7 mg/dl
• Rises with age 3
Absent in
Humans

4. Gout
• Gout may run in families.
• It is more common in men (>5:1), and in women after menopause.
– Low water solubility at low pH.
• When blood levels are high, it precipitates and deposits in joints,
kidney and subcutaneous tissue (tophy).
• Tophi are lumps below the skin around joints or in other places.
They may drain chalky material. Commonly, they occur on the ear,
fingers and toes and around the ankle and elbow.
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Tophi-(Latin) Stone

5. Joints affected
MSU crystals preferentially deposit in
• peripheral connective tissues in and around synovial
joints,
• initially favoring the lower rather then upper limbs
• Especially targeting, the MTP joint and then the small
joints of hands and feet.
As the crystals deposit and enlarge, there is progressive
involvement of more proximal sites and potential for
cartilage and bone damage is seen with secondary OA.
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6. Gout
• If too much uric acid builds up
in the fluid around the joints
(synovial fluid), uric acid
crystals form.
• These crystals cause the joint to
swell up and become inflamed.
• Mostly it is observed on the
feet, though it also affects the
wrists, fingers, elbows, knees,
ankles and feet.
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7. Symptoms of Gout:
• Asymptomatic stage:
– In this stage urate levels increase in the blood but it has no any specific signs and
symptoms.
• Acute stage: (Requires immediate treatment)
– swelling
– sudden attack of joint pain
– joints feel hot, tender and look dusty red or bruised
– Malaise, fever, raised ESR & neutrophils
• Chronic stage:
– Urate deposits in the cartilage, membranes between the bones, tendons and soft
tissues and patient feels painful joints.
– Skin over the deposits increase sores and release white pus.
– Joint inflexibility, limited motion of affect joint
– Causes progressive disability and permanent deformities.
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8. Gout Types
MSU gout (Mono sodium Urate) is most common type and is generally
simply known as gout; however, other types of gout also exists:
1. HA Gout (Calcium Hydroxyapatite)
2. Calcium Oxalate Gout (Rare)
3. Pseudo Gout/CPPD Arthritis (Common)
(CPPD-Calcium pyrophosphate dihydrate)
• Clinically indistinguishable symptoms
• Definitive diagnosis: Aspiration analysis of synovial effusion- type of
microcrystals
• Treatment of other types of gout is all symptomatic and similar to MSU Gout
– NSAIDs, Colchicine and Glucocorticosteroids.
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9. Secondary hyperuricaemia
Disease states
• It occurs in different disease states like-
– Leukaemias,
– Lymphomas,
– Polycythaemia,
– Especially when treated with chemotherapy or
radiation: due to enhanced nucleic acid
metabolism and uric acid production.
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10. Secondary hyperuricaemia
Drugs that precipitate acute gout
• Thiazides, frusemide, ethacrynic acid
• Ethambutol, pyrazinamide
• Levodopa
• Cytotoxic drugs
• Ethanol, Isotretinoin, salicylate (low),
clofibrate, cyclosporin, etc.
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11. Manipulating Serum Uric Acid Levels
(Allopurinol, febuxostat)

12. Therapy
A. For acute gout:
– NSAIDs: Indomethacin, Naproxen, Piroxicam,
Diclofenac
• Colchicine
• Glucocorticosteroids
B. For chronic gout:
• Uricosuric drugs: Probenecid, Sufinpyrazone
• Uric acid synthesis inhibitors: Allopurinol
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13. NSAIDS
• Strong antiinflammatory drugs like- Indomethacin, Naproxen,
Piroxicam, Diclofenac is given in relatively high and quickly
repeated doses.
• Terminate attack in 12-24 hrs, longer than colchicine, but better
tolerated.
• Naproxen and piroxicam specifically inhibit chemotactic
migration of leucocytes into the inflamed joint.
• Even once attack is over, low dose continued till control of
hyperuricemia is achieved.
• In chronic gout, for initial coverup till effect builds up with other
drugs.
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14. Colchicine
• An alkaloidal drug, that suppresses gouty inflammation.
M/A
• The process of release of glycoprotein, normally
following phagocytosis of urate crystals which
aggravates inflammation is inhibited.
• By binding to fibrillar protein tubulin, it inhibits
granulocyte migration into the inflamed joint and
thus interrupts vicious cycle.
• It also inhibits the mast cell release of histamine.
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15. Colchicine
Other actions of colchicine are:
a) Antimitotic: Causes metaphase arrest: tried for
cancer chemotherapy but abandoned due to
toxicity.
b) Increases gut motility through neural mechanisms
• No analgesic or anti-inflammatory actions. Also
does not have any effect on blood uric acid levels-
does not inhibit synthesis or promote the excretion
of uric acid.
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16. Colchicine
Use
Treatment of acute gout
Fastest acting drug in gout, 1mg p/o, increase to 6mg max or till
diarrhoea occurs. Toxicity high so NSAIDs preferred. Maintenance
dose (0.5-1mg/day) given for 4-8 weeks.
Definitive diagnosis of gout
As a therapeutic trial for definitive diagnosis of gout, because response
to colchicine is specific to gout.
Prophylaxis-
Low dose 0.5-1mg/day prevents further attacks, NSAIDs preferred.
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17. Colchicine
Toxicity
Dose related, relatively high toxicity
Nausea, vomiting
Watery or bloody diarrhoea, abdominal cramps
(Drug in intestine and mitosis inhibition of mucosa.)
High dose:
Kidney damage, Intestinal bleeding,
CNS depression
Death from muscular paralysis & respiratory failure.
Chronic therapy : Not recommended
Aplastic anemia, agranulocytosis
Myopathy and Alopecia (hair loss)
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18. Corticosteroids
• Potent immunosuppressant and anti-inflammatory
• Given in refractory cases and in those not tolerating
NSAIDs or colchicine.
• Intra-articular injection of soluble steroid suppresses
the symptoms of acute gout.
• Very effective and produce rapid response as
colchicine, but reserved for patients with Renal
failure/history of peptic ulcer bleeding.
• Prednisolone 40-60 mg may be given in one day,
followed by tapering doses over few weeks.
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19. Corticosteroids
• Prednisolone 4x potency hydrocortisone
• Methyprednisolone slightly more potent than prednisolone
• S/E-
– Stomach irritation, such as indigestion
– Tachycardia, nausea, insomnia, metallic taste
– Weight gain, thinning skin, muscle weakness, weakening of
bones (osteoporosis), high blood pressure
– Oral corticosteoids increase vulnerability to infection by
viruses chicken pox, measles.
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20. • In severe cases with excruciating pain, an opioid
analgesic such as pethidine 100mg IM may be
necessary.
• Addiction liability prevents repeated use.
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21. Treatment of
Chronic Gout
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Drugs used in Chronic gout should not be
given during acute gout .
During initial 1-2 months treatment with these
drugs attacks of acute gout may precipitate
due to fluctuating plasma urate levels.
NSAIDs or Colchicine may be required at
start.

22. URIC ACID SYNTHESIS INHIBITOR
Allopurinol
Purine antimetabolite drug
Hypoxanthine anlogue: Lack antineoplastic axn
M/A
• Inhibitor of xanthine oxidase, enzyme responsible for uric acid synthesis.
• It has short T1/2 2 hrs, but it gives active metabolite Alloxanthine T1/2 24
hrs. It is a noncompetitive inhibitor of uric acid synthesis in vivo.
• During allopurinol administration, plasma concentration of uric acid
is reduced and that of hypoxanthine and xanthine is somewhat
increased. In place of uric acid alone all 3 oxipurines which are more
water soluble, are excreted in urine.
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23. Axn of Allopurinol
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24. URIC ACID SYNTHESIS INHIBITOR
Allopurinol
Uses
• DOC in chronic gout
• Used in both over producers and under excretors of uric acid,
particularly more severe cases, with tophi or nephropathy.
• With long-term allopurinol therapy, tophi gradually disappear &
nephropathy is halted, even reversed.
• To stop secondary hyperuricaemia.
• To potentiate 6-mercaptopurine and azathioprine in cancer therapy.
• Inhibits Leishmania (Kala-azar) by altering its purine metabolism,
therefore, used as adjuvant to Sodium Stibogluconate in resistant
cases.
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25. URIC ACID SYNTHESIS INHIBITOR
Allopurinol
A/E Uncommon
Hypersensitivity rxn- rashes
Fever, malaise, and muscle pain
Renal impairment increases A/Es.
Gastric irritation, headache, nausea and dizziness
Stevens-Johnsons syndrome rare & serious
Rarely liver damage
Precautions
Drink more fluid
C/I
Hypersensitive patients
Pregnancy and lactation
Caution
Renal or hepatic disease
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26. NOTE: They can be hazardous in:
• Urate overproducers (>800mg/24hr)
• Urine flow consistently < 1ml/min
• Creatinine clearance < 50 ml/min
• History of renal calculi
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URICOSURIC DRUGS

27. URICOSURIC DRUGS
Probenecid
It is an agent which promotes the excretion of uric acid in
the urine.
M/A
Uric acid is largely reabsorbed by active transport, and
only 10% of filtered load is excreted in urine.
Probenecid, being highly lipid soluble organic acid,
competitively blocks uric acid’s active reabsorption and
causes it to be excreted out. The therapeutic dose needs to
be a bit higher, since small doses decrease urate excretion
instead.
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28. URICOSURIC DRUGS
Probenecid
Uses
1. Chronic gout and hyperuricaemia
Second line drug, adjuvant to Allopurinol. It gradually lowers blood urate
level; arthritis, tophi may take months to resolve.
Probenecid and other uricosurics are ineffective in the presence of renal
insufficiency (serum creatinine > 2 mg/dl). Plenty of fluids should be given
with probenecid to avoid urate crystallization in urinary tract.
2. To prolong penicillin or ampicillin action
By enhancing and sustaining their blood levels, e.g. in gonorrhoea.
However, penicillin being relatively non-toxic is rather given in high doses
and this is not seen much practically.
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29. URICOSURIC DRUGS
Probenecid
A/E
Generally well tolerated.
Dyspepsia
Rarely rashes and hypersensitivity seen
Toxic dose: Convulsions and respiratory failure.
Caution
Peptic ulcer
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30. URICOSURIC DRUGS Sulfinpyrazone
• Uricosuric agent with no analgesic or anti-inflammatory action
• Its uricosuric action is additive with probenecid but antagonised by
salicylates.
• Uricosuric action lasts for 6-10 hours.
• It also inhibits platelet aggregation.
Uses
In chronic gout- results are similar to probenecid
Dose 100-200 mg BD, to max 800mg/day.
A/E
Gastric irritation
Rarely rashes and hypersensitivity seen
C/I
Peptic ulcer
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31. Non-pharmacological intervention
• Avoid alcohol and soda
• Reduce purine-rich foods especially, sardines, oils, organ
meat (liver, kidney, and sweetbreads), legumes (dried beans
and peas), gravies, mushrooms, spinach,cauliflower, and
baking or brewer's yeast.
• Avoid fatty foods such as salad dressings, ice cream, and
fried foods.
• Eat enough carbohydrates.
• If trying to lose weight, lose it slowly. Quick weight loss may
cause uric acid kidney stones to form.
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32. That’s All
ENJOY
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