DIARRHOEALoose bowel movements resulting into the frequent passageof water, uniformed stools with or without mucous and blood.ClassificationOsmotic diarrhoeaSomething in the bowel is drawing water from the body intothe bowel.Eg; Sorbitol is not absorbed by the body but draws waterfrom the body into the bowel, resulting in diarrhoea.
Secretory diarrhoeaOccurs when the body is releasing water into the bowel,many infections, drugs causes secretory diarrhoea.Exudative diarrhoeaDiarrhoea with the presence of blood and pus in the stool.This occurs with inflammatory bowels disease (IBD), such ascrohn’s disease or ulcerative colitis etc.
Acute diarrhoeaSudden onset in a previously healthy personLasts from 3 days to 2 weeksSelf-limitingResolves without sequelaeChronic diarrhoeaLasts for more than 3 weeks.Associated with recurring passage of diarrhoeal stools, fever,loss of appetite, nausea, vomiting, weight loss, and chronicweakness
DRUG THERAPYi. Specific antimicrobial drugsii. Non specific antidiarrhoeal drugsORALREHYDRATIONTHERAPY
Specific anti microbial drugsA. Antimicrobials are of no valueDue to non infective causes such asIrritable bowel syndromeColic diseasePancreatic enzyme deficiency etcRota virus causes acute diarrhoea, specially in children
B. Antimicrobials are regularly usefulcholeraTetracyclines,chloramphenicoletcClostridiumdifficileVancomycin,metronidazole etcamoebiasisMetronidazole,dioxonidfuroate
NON SPECIFIC ANTIDIARROEALS1.Adsorbents Have the power of adsorbing gases,toxins etc without any chemicalreactions.Eg; kaolin, pectin, calcium carbonate. Etc
2.Anti secretory Agents which reduce the secretionEg; aspirin, sulphasalazine, bismuth sub salicylate, atropineetc.3.Antimotility drugs Increase small bowel tone and segmenting activity. Helps reabsorption of water by delaying intestinal transittimeEg: codeine, loperamide, diphenoxylate etc
Functions of Antidiarrhoeal DrugsDecrease irritation to the intestinal wallBlock GI muscle activity to decrease movementAffect CNS activity to cause GI spasm and stopmovementRelief of symptoms and fluid & electrolyte loss
Many OTC antidiarrhoeal drugs, contain limited amountsof opioids (loperamide) aluminium hydroxide, kaolin andpectin.PRECAUTIONS Care should be taken when using antidiarrhoeals if thecause of the diarrhoea is bacterial as this allows thebacterial toxin to remain in the body. Excess use may cause constipation
Non Specific Antidiarrhoeal DrugsAdsorbents Coat the walls of the GI tract Bind to the causative bacteria or toxin, which is theneliminated through the stool Examples: bismuth subsalicylate, kaolin-pectin, activatedcharcoal.
Side EffectsIncreased bleeding timeConstipation, dark stoolsConfusion, twitchingHearing loss, tinnitus, metallic taste, blue gums
Anti secretory Agents which reduce the secretion Decrease intestinal muscle tone and peristalsis of GI tract Result: slowing the movement of faecal matter through theGI tract Examples: belladonna alkaloids, atropine, sulphasalazine,hyoscyamine
Antimotility drugsDecrease bowel motility and relieve rectal spasmsDecrease transit time through the bowel, allowing moretime for water and electrolytes to be absorbedExamples: codeine, loperamide, diphenoxylate
OOHOHNH2NaNO2/HClClN OOHOHN+HSOON NNH2HNNOSNNOHOOHOSynthesis of Sulphasalazine
Metabolism of SulphasalazineSulphasalazine[H]GutNH2OHOOH5- Amino salicylic acid+HOSNNOProdrug, having low solubility and poorly absorbed fromileum. The azo bond split by column bacteria into Sulfa pyridineand 5-amino salicylic acid.Blocks cyclooxgenase and lypooxygenase pathway andreduce mucosal secretion.
CONSTIPATIONConstipation is the infrequent and/or unsatisfactorydefecation fewer than 3 times per week.Abnormally infrequent and difficult passage of faeces throughthe lower GI tractSymptom, not a diseaseDisorder of movement through the colon and/or rectum
CAUSES OF CONSTIPATIONDiet Lack of exercise Age Irregular bowel habits Drug induced Disease States/ConditionsSpasm of sigmoid colonDysfunction of myenteric plexus
SYMPTOMS OF CONSTIPATIONInfrequent defecationNauseaVomitingAnorexiaFeeling full quicklyStools that are small, hard, and/or difficultto evacuateRectal bleedingWeight loss (in chronic constipation)
• Mild action,elimination of softstools but formedstools.Laxative oraperients• Stronger actionresulting in morefluid evacuation.Purgative orcatharticLAXATIVESDrugs that promote evacuation of bowels.Based on intensity of action
4. Osmotic purgative Magnesium salts, lactuloseetcBulk Forming LaxativesImprove stool consistency and frequency with regular useEnsure good fluid intake to prevent faecal impactionOnset of action 2-3 daysSide Effects may include bloating, flatulence, distension
Stool SoftenersMay be useful with anal fissures of haemorrhoidsLiquid paraffin is not recommended for treatment ofconstipation- risk of aspiration and lipid pneumonia- long term use may result in depletion of VitaminsA, D, E and K
Stimulant Laxatives Increase intestinal motility by stimulating colonic nerves Useful with opioids Onset of action 8-12 hours Development of tolerance is reported to be uncommon Generally considered 2nd line therapy in elderly due to riskof electrolyte disturbances Other adverse effects include cramping, diarrhoea,dehydration
Osmotic LaxativesIncrease fecal water contentResult: bowel distention, increased peristalsis,and evacuationImproving stool frequencyOnset of action – up to 48 hoursMetabolized by bacteria flatulence
OONOOCH3 CH3BisacodylONCH + 2C6H5OHH2SO4(CH3CO)2ONOOCCH3CCH3OOSynthesis of Bisacodyl
OOOHOHOOO+OHOHH2SO4OOOHOHphathalic anhydridephenolphenolphthaleinSynthesis of phenolphthaleinPhenolphthalein
OHNHN NHNHCH3TegaserodIt is 5HT4 agonist used for the management ofirritable bowel syndrome and constipation
CONCLUSIONGood nutrition and hygiene can prevent mostdiarrhoea.Patients should be instructed to increase fluidintake and participate in regular exercise to preventconstipation.
REFERENCE1.Text Book of Medicinal chemistry by V.Alagarsamy;volume-II;page no:11372.Bently and Driver’s text book of pharmaceutical chemistry8th edition revised By L M ANTHERDEN page No. 724, 625.3.Essentials of medicinal pharmacology by K D TRIPATHI 6thedition page No. 6514.Clinical Pharmacy and Therapeutics, 4th edition by RogerWalker, Cate Whitelsia Page No: 824- 8325. www.wickipedia.org