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Gastrointestinal drugs. Department of pharmacology Liming zhou 2010,spring. classification. Drugs for treatment of peptic ulcers Drugs for adjusting the function of digestion Drugs promoting gastrointestinal motility Antiemetic drugs laxatives.
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Gastrointestinal drugs Department of pharmacology Liming zhou 2010,spring
classification • Drugs for treatment of peptic ulcers • Drugs for adjusting the function of digestion • Drugs promoting gastrointestinal motility • Antiemetic drugs • laxatives
Drugs for peptic ulcers Classification of peptic ulcer: • Duodenal (DU) Gastric (GU) • Role of pepsin in peptic ulcer disease: • Secreted gastric acid plus effects of pepsin promote tissue injury
Peptic ulcer disease: an imbalance between aggressive factors (gastric acid pepsin bacteria) and protective factors (gastric mucus, bicarbonate, prostaglandins) • Regulation of gastric acid secretion-- many factors (chemical, neural, hormonal)
Stimulation: • Gastrin-most potent stimulant • Activation of postganglionic vagal fibers
Drugs for peptic ulcers-----antacidsAction • Neutralize secreted acid • Reduce gastric acidity Pepsin inactive Reduce destroy factors
Drugs for peptic ulcers-----antacids • A magnesium hydroxide(氢氧化镁) • B magnesium trislilicate(三硅酸镁) • C aluminum hydrocide(氢氧化铝) • D Calcium carbonate(碳酸钙) • F Sodium bicarbonate(碳酸氢钠)
1 NaHCO3+HCl NaCl+H2O+CO2 • 2 Al(OH)3 aluminium hydroxide • Al(OH)3+3HCl AlCl3 +3H2O • 3 Mg(OH)2 magnesium hydroxide • Mg(OH)2+2HCl MgCl2 +2H2 O • 4 Mg2Si3O8 magnesium trisilicate • Mg2Si3O8+4HCl 2MgCl2+3SiO2+2H2O • 5 CaCO3 calcium carbonate • CaCO3+2HCl CaCl2+H2O+CO2
Gastric antisecretory drugs • antagonisit of H2 receptor ↓ • decrease the H+ secretion • Basal gastric acid food-stimulated gastric acid
H2 Receptor Antagonists • A cimetidine (西米替丁) + • B ranitidine (雷米替丁)++ • C famotidine(法莫替丁)+++ • Effective inhibitor of stimulated and non-stimulated gastric acid secretion • Healing rates: similar between antacids and H2 receptor antagonists
Effective inhibitor of stimulated and non-stimulated gastric acid secretion • Healing rates: similar between antacids and H2 receptor antagonists
Mucosal protective agents • Prostaglandins • reduction in basal and stimulated gastric acid secretion; • enhanced mucosa resistance to injury (PGE1/PGE2).
Mucosal protective agents • Bismuth compounds • Mechanism of Action • cytoprotective effects • compounds bind to the ulcer base, stimulating mucus and prostaglandin production • antibacterial effect • inhibition of proteolytic, lipolytic, and urease activities • Coating and protecting the ulcer crater
Clinical use of Bismuth compounds • In monotherapy: • ------- eradicate H. pylori in about 20% of patients • combination with antibiotics • -------eradicate H. pylori in up to 95% of patients.
Sucralfate • binds to ulcer bed (granulation tissue, not to gastric or duodenal mucosa) • decreases proton diffusion to the ulcer base • may increase endogenous tissue prostaglandins and may bind epidermal growth factors and other growth factors-- improving mucosal defense
antimicrobials • activity against H.pylori • clarithromycin, amoxicillin, tetracycline
Drugs for adjusting the function of digestion • drugs of aid digestive • A pepsin • B pancreatin • C lactasin
antiemetic drugs and drugs promoting gastrointestinal motility • antiemetic drugs: • H-1 receptor blocker : diphenhydramine • Chloropromazine • M-receptor blocker : scopolamine
drugs promoting gastrointestinal motility • Metoclopramide (甲氧氯普胺): • domperidone (多潘立酮)blocking D2-receptor • Cisapride(西沙比利)
Metoclopramide (甲氧氯普胺) • Blocking the DA2 receptor in CTZ • Blocking the DA2 receptor in Gastrointestinal
domperidone (多潘立酮) • blocking DA2-receptor in Gastrointestinal
Cisapride(西沙比利) • Increase release of the Ach
antidiarrheal drugs • opium preparation • Laxative Drugs magnesium sulfate sodium sulfate