Management of Peptic Ulcer Disease

Transcription

1 Management of Peptic Ulcer Disease GIT and liver module (Semester IV) Dr. Muhammad Azhar Mughal Department of Pharmacology Jinnah Sindh Medical University, Karachi

2 PGE 2 ACh Misoprostol + Histamine Ranitidine Gastrin _ Proglumide _ M 3 + PGE receptor Ca ++ + _ Adenyl cyclase ATP camp + + H 2 + Ca ++ + Gastrin receptor Protein Kinase (Activated) K + + H + Omeprazole _ Proton pump Gastric acid Parietal cell Lumen of stomach _ Antacid

3 Overview of Peptic Ulcer Peptic ulcer disease (PUD) refers to painful sores or ulcers in the mucosal lining of the stomach or the first part of the small intestine, the duodenum secondary to pepsin and gastric acid secretion. LECTURE OUTLINES

4 Antacids Weak bases that neutralize acid Also inhibit formation of pepsin (As pepsinogen converted to pepsin at acidic ph) Present day antacids : Aluminium Hydroxide Magnesium Hydroxide OTC drug for symptomatic relief of dyspepsia Duration of action : 30 min when taken in empty stomach 2 hrs when taken after a meal Side effects : Al3+ antacids constipation (As they relax gastric smooth muscle & delay gastric emptying) Mg2+ antacids Osmotic diarrhea. In renal failure, Al3+ antacid Aluminum toxicity & Encephalopathy

5 Antacids Common additives Simethicone Decrease surface tension, thereby reduce bubble formation Added to prevent reflux. Alginates - Form a layer of foam on top of gastric contents & reduce reflux Oxethazaine Surface anaesthetic Antacid Interactions Adsorb drugs and form insoluble complexes that are not absorbed. Clinical importance: Interactions can be avoided by taking antacids 2 hrs before or after ingestion of other drugs. Now answer this question Is it rational to combine aluminium hydroxide and magnesium hydroxide in antacid preparations?

6 Answer Combination provides a relatively fast and sustained neutralizing capacity. (Magnesium Hydroxide Rapidly acting Aluminum Hydroxide - Slowly acting ) Combination preserves normal bowel function. (Aluminium Hydroxide constipation Magnesium hydroxide diarrhea ) Histamine H2 Receptor Antagonist Reversible competitive inhibitors of H2 receptor Highly selective, No action on H1 or H3 receptors Very effective in inhibiting nocturnal acid secretion (as it depends largely on Histamine) Modest impact on meal stimulated acid secretion (As it depends on gastrin, acetyl choline and histamine)

7 Cimetidine Ranitidine Famotidine Nizatidine Bioavailability >90 Relative Potency Half life (hrs) Duration of action (hrs) Inhibition of CYP 450 Dose mg(bd) H2 Blockers Side effects H2 blockers are extremely safe drugs. Incidence is 3% and include diarrhea, headache, fatigue, myalgias, and constipation. CNS EFFECTS: Mental status changes (confusion, hallucinations, agitation) may occur with I/V administration of H2 blockers, especially in patients in ICU who are elderly or who have renal or hepatic dysfunction

8 ENDOCRINE EFFECTS Cimetidine inhibits binding of dihydrotestosterone to androgen receptors. Inhibits metabolism of estradiol, and increases serum prolactin levels. Gynecomastia or Impotence in men and galactorrhea in women (when used long-term or in high doses). These effects are specific to Cimetidine and do not occur with the other H2 antagonists. PREGNANCY AND NURSING MOTHERS Not known harmful effects on the fetus. Cross the placenta- Avoid in pregnancy unless absolutely necessary. The H2 blockers are secreted into breast milk and may affect nursing infants.

9 Drug-Drug Interactions Cimetidine interferes hepatic cytochrome P450 enzymes (CYP1A2, CYP2C9, CYP2D6, and CYP3A4) activity. Cimetidine inhibits CYP450 & increases conc. of Warfarin, Theophylline, Phenytoin, Ethanol. Proton Pump Inhibitors Most effective drugs in anti-ulcer therapy Irreversible inhibitor of H+ K+ ATPase Pro-drugs requiring activation in acid environment Weakly basic drugs & so accumulate in canaliculi of parietal cell Activated in canaliculi & binds covalently to extracellular domain of H+ K+ ATPase Acid secretion resumes only after synthesis of new molecules

10 Proton Pump Inhibitors Omeprazole Esomeprazole Lansoprazole Pantoprazole Rabeprazole Proton Pump Inhibitors Kinetics Given as enteric coated granules in capsule or enteric coated tablets Pantoprazole also given intravenously Half life 1.5 hrs Since it requires acid for activation - given 1 hr before meals Other acid suppressing agents not co-administered P.P.I. Side effects & Interactions Extremely safe drugs Causes hypergastrinemia which leads to carcinoid tumor in rats But no evidence of such tumors in man Inhibit CYP 450 & hence metabolism of warfarin, phenytoin, etc Pantoprazole & Rabeprazole have no significant interactions

11 Now Answer this Question A patient comes to your clinic at midnight complaining of heart burn. You want to relieve his pain immediately. What drug will you choose? Answer : Antacids Explanation : Antacids neutralize the already secreted acid in the stomach. All other drugs act by stopping acid secretion and so may not relieve symptoms at least for 45 min. Mucosal Protective Agents Mucosal Protective Agents Sucralfate Misoprostol Colloidal Bismuth compounds

12 Sucralfate Salt of sucrose complexed to sulfated aluminium hydroxide In acidic ph polymerizes to viscous gel that adheres to ulcer crater Taken on empty stomach 1 hr. before meals Concurrent antacids, H2 antagonist avoided ( as it needs acid for activation ) Misoprostol PGE1 analogue Modest acid inhibition Stimulate mucus & bicarbonate secretion Enhance mucosal blood flow Approved for prevention of NSAID induced ulcer Diarrhea & cramping abdominal pain 20 % Not so popular as PPIs and are more effective & better tolerated

13 Colloidal Bismuth Compounds Coats ulcer, stimulates mucus & bicarbonate secretion Direct antimicrobial activity against H. Pylori May cause blackening of stools & tongue Not used for long periods bismuth toxicity Available compounds : Bismuth subsalicylate in USA Bismuth subcitrate in Europe Bismuth dinitrate Now answer this question A pregnant lady (first trimester) comes to your clinic with peptic ulcer disease. Which drug will you prescribe to her for peptic ulcer disease. Answer : Antacids or Sucralfate Explanation ; H2 antagonists cross placenta and are also secreted in breast milk. Safety of Proton pump inhibitors is not established in pregnancy. Misoprostol causes abortion.

14 Can you identify these people? Nobel prize Medicine 2005 Discovery of H. Pylori & its role in ulcer Barry J Marshall J. Robin Warren

15 Eradication of H. Pylori Triple Therapy The BEST among all the Triple therapy regimen is Omeprazole / Lansoprazole - 20 / 30 mg b.d Clarithromycin mg b.d Amoxycillin / Metronidazole - 1gm / 500 mg b.d Given for 14 days followed by P.P.I for 4-6 weeks Short regimens for 7-10 days not very effective Triple Therapy cont Some other Triple Therapy Regimens are Bismuth subsalicylate 2 tab qid Metronidazole mg qid Tetracycline mg qid Ranitidine Bismuth citrate mg b.d Tetracycline mg b.d Clarithromycin / Metronidazole mg bd

16 Quadruple Therapy Given when Triple Therapy fails Omeprazole / Lansoprazole - 20 / 30 mg bd Bismuth subsalicylate - 2 tabs qid Metronidazole mg qid Tetracycline mg qid Now you have learnt about drugs used for treating peptic ulcer? Are there any drugs that can cause peptic ulcer? Drugs causing peptic ulcer Non Steroidal Anti Inflammatory Drugs (NSAIDs) Glucocorticoids Cytotoxic agents Stress induced ulceration after head trauma Cushing s ulcer Stress induced ulceration after severe burns Curling s ulcer