3. drug affecting git motility rt h

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Pharmacology …

Third Year

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  • 1. Drug affecting MOTILITY of GIT
  • 2. Antiemetic agentsAntiemetic agents
  • 3. Antiemetic agents • Antiemetics are drugs given to prevent or releive nausea and vomiting • They exert their effects on the vomiting center, the cereberal cortex, the CTZ, or the vestibular appratus • The neurotrasmitters involved in controlling or preventing nausea and vomiting include dopamine, acetylcholine, histamine and serotonin
  • 4. Antiemetic drugsAntiemetic drugs H 1 antagonists: Meclizine, Diphenhydramine, Dimenhydrinate Muscarinic receptor antagonists: Hyoscine. Dopamine antagonists: -Phenothiazines e.g. chlorpromazine -Butyrophenones e.g. Haloperidol. -Metoclopramide (prokinetic) -Domperidone (prokinetic) 5HT3 antagonists e.g. Ondansetron (Zofran) Effective in vomitting due to anti-cancer chemotherapy) Corticosteroids: (dexamethazone)
  • 5. Metoclopramide (Reglan)Metoclopramide (Reglan) It blocks central dopaminergic D2- receptors and in high doses it blocks 5-HT3 receptors It has antiemetic action It accelerate gastric emptying (prokinetic) It raise lower esophageal sphincter pressure It increase intestinal peristalsis
  • 6. MetoclopramideMetoclopramide Indications  Vomiting due to anesthesia, uremia, drugs Rapid emptying of stomach before emergency surgery and labour  Gastro esophageal reflux and esophagitis. GIT investigation: e.g. endoscopy
  • 7. MetoclopramideMetoclopramide Side effects - Sedation, diarrhea . - Involuntary movements e.g parkinsonism - Hyperprolactinemia . DOMPERIDONE (MOTILIUM) Similar to Metoclopramide with less CNS effects and does not cross BBB
  • 8. Choice of anti-emeticsChoice of anti-emetics
  • 9. EmeticsEmetics Agents that induced reflex vomiting e.g. syrup ipecac, apomorphine and hypertonic salt solution. Uses : Useful for removing unabsorbed toxin from the stomach
  • 10. Prokinetics drugsProkinetics drugs Drugs that promote gastrointestinal motility without purgation
  • 11. Cisapride (prepulsid) • It releases acetylcholine from cholinergic neurons in the enteric nervous system and mesenteric plexus. • It hastens esophageal clearance and raise lower esophageal sphincter pressure. • Uses • Gastro esophageal reflux
  • 12. Anti-spasmodicAnti-spasmodic librax (Clidinium plus chordiazepoxide )
  • 13. Anti-cholinergic drugs Hyoscine-N-butyl bromide Competitively block muscarinic M3 receptors in GI Decrease peristalsis & constrict sphincters Adverse effects: Dry mouth, constipation, tachycardia, palpitation, raised IOP & urine retention Caution: elderly patients (glaucoma) & male patients (prostatic hypertrophy)
  • 14. LaxativesLaxatives A laxative induces defecation and is used in the prevention and treatment of constipation Constipation is best prevented with high fiber diet, adequate fluid intake & regular exercise Over use of laxative may lead to laxative habit or dependence Indications of laxatives: 1- Constipation 2- Hepatocellular failure (Magnesium sulphate, lactulose). 3- To prepare the bowel prior to X-ray on GIT and proctoscopic or colonoscopic procedures 4- To hasten excretion of poisonous substances in the alimentary tract.
  • 15. Laxatives ClassificationLaxatives Classification Dioctyl, Liquid paraffin and Glycerin suppository
  • 16. Bulk laxativesBulk laxatives dietary fibers (fruits and vegetables) Methyl cellulose, bran and agar. they are non- digestible and have capacity to retain water in gut lumen thus enhance the bulk and moisture content to stool May cause intestinal obstruction, take sufficient water to prevent obstruction
  • 17. Osmotic laxativesOsmotic laxatives Lactulose Synthetic disaccaride , non digestable and not absorbed in the small intestine In the colon it retain water in lumen by osmosis causing distension and reflex increase in peristalsis uses Constipation hepatic encephalopathy
  • 18. Irritant or stimulant laxativesIrritant or stimulant laxatives Castor oil •Very irritating to the gut, converted to recinoleic acid that promptly increases peristalsis. •Rapid strong complete evacuation of colon •Uses: preparation of the patient for radiological examination Bisacodyl Stimulation of peristalsis Act on the large intestine producing a semi fluid stool Side effects: Stimulant laxatives may cause diarrhea, dehydration and electrolyte impalance, megacolon ,ulcerative colitis, ↑ menstrual blood flow and abortion. abdominal cramps and the potential for atonic colon with prolonged use Avoid in intestinal obstruction & pregnancy
  • 19. Stool softenersStool softeners Dioctyl Softens of stool mass by lowering surface tension of stool to enter more readily and softens the faces Liquid paraffin: (physical and lubricant agent). •It coats intestine so decreasing water absorption Adverse effects •Infiltration in liver, leakage and accumulation in regional lymph nodes •Long term use causes deficiency of Vit. A, D, E & K ( fat soluble vitamins) Glycerin suppository It is considered as stool softener. It acts osmotic agent promoting stool evacuation “
  • 20. Drug therapy of diarrhea
  • 21. Treatment of diarrheaTreatment of diarrhea
  • 22. Maintenance of fluid and electrolytes balance Maintenance of fluid and electrolytes balance • It is the first priority and many cases require no other treatment. • Dehydration is a common complication of diarrhoea Balanced solution containing Na Cl + K Cl+ glucose + Na citrate is used as oral rehydration solution For mild to moderate dehydration For sever dehydration: IV fluids 5% dextrose & normal saline KCl &/or Na HCO3, when hypokalemia &/or acidosis
  • 23. Non-specific antidiarrhealNon-specific antidiarrheal
  • 24. AdsorbentsAdsorbents kaolin, pectin, active charcoal and bismuth subsalicylate these agents act by adsorbing intestinal toxins or microorganisms and/or by coating or protecting the intestinal mucosa. Adverse effects: Can cause constipation They can interfere with the absorption of other drugs.
  • 25. Opiates and opioid containing preparation Opiates and opioid containing preparation Diphenoxylate and Loperamide Action: have opioid-like actions on the gut, activating presynaptic opioid receptors in the enteric nervous system to inhibit acetylcholine release and decrease peristalsis. Side effects include drowsiness, abdominal cramps, and dizziness