DrugsAffectingtheGastrointestinalystem分析课件.ppt

Drugs Affecting the Gastrointestinal System Drugs Affecting the Gastrointestinal System Antiulcerants Digestives Antiemetics Purgatives Antidiarrheals Cholagogues Peptic Ulcers Common disease，incidence rate: 10%~12%. Pathogenesis of ulcers Aggressive Factors Defensive Factors Peptic Ulcers Therapy Purpose： Therapy is directed at enhancing host defense or eliminating aggressive factors; i.e., H. pylori. Drugs Used in Peptic Ulcers Antacids Inhibitors of gastric acid production H2-receptor antagonists Proton pump inhibitors Muscarinic antagonists Gastrin receptor antagonist Mucosal Protectants Anti-Helicobacter pylori. drugs Drugs Used in Peptic Ulcers Proton pump inhibitors ：omeprazole Gastrin receptor antagonist ：proglumide Mucosal Protectants ：misoprostol Anti-Helicobacter pylori. Drugs ：antibiotics Antacids Antacids Magnesium hydroxide Magnesium trisilicate Aluminum hydroxide Calcium carbonate Sodium bicarbonate H2-receptor antagonists Mechanism of action Competitively block the histamine (H2) receptor of acid-producing parietal cells rendering cells less responsive to not only histamine but also to the stimulation of acetylcholine and gastrin. Also up to 90% inhibition of vagal stimulated and gastrin stimulated acid secretion. complete inhibition has not been shown H2-receptor antagonists Four FDA-approved: Cimetidine （Tagamet?） Ranitidine （Zantac?） Famotidine （Pepcid?） Nizatidine （Axid?） Roxatidine H2-receptor antagonists Therapeutic effects: Promote the healing of gastric and duodenal ulcers Gastroesophageal reflux dz [GERD] Upper GI bleed [GIB] May be effective in stress ulcers peptic esophagitis H2-receptor antagonists Side effect: Overall low 3% CNS: 1% total headache, lethargy ，confusion, depression，hallucinations ENDO： Impotence ，increased prolactin ，gynecomastia HEME: Thrombocytopenia Muscarinic antagonists Atropine： Block the M1