24.作用于消化系统的药物——山东大学药理学英文课件

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1、 A benign, localized defect in the mucosa of any part of the gastrointestinal tract. duodenal ulcer gastric ulcer The most important symptom is abdominal pain and discomfort. The atypical symptoms are abdomen distention, inappetence, belching, reflux of gastric acid. The severe complications are hem

2、orrhage, perforation, obstruction and canceration. although the pathogenesis of peptic ulcer disease is not fully understood, the theory that the balance between mucosal defense and injury is broken are recognized. Pathogenesis of peptic ulcer1. Aggressive factors Helicobacter Pylori ( H. Pylori) ga

3、stric acid and pepsin 2. Defensive factors mucus-bicarbonate barrier prostaglandinsIn 1983, H. pylori was found by two Australians, Marshall and Warren. Now, it is believed that H. pylori is the most important pathogenic factor to peptic ulcer. “No H.P., no ulcer. And the two men won the noble prize

4、 for the important findings in 2005.flagellumPepsin can decompose protein molecule. But its activity is depended on the pH value. When local pH value elevates to 4, pepsin cant work well. Gastric acid is the key-factor of the formation of peptic ulcer. we can also say that “No acid, no ulcer. The ep

5、ithelial layer of the mucosa is composed of tightly adjoined cells that are specialized for existence in an acid medium. Their tight junctions, synthesis of PGs and secretion of mucus and bicarbonate all contribute to maintenance of the epithelial barrier. mucus Prostaglandins are thought to enhance

6、 resistance to injury by maintaining blood flow to the mucosa. Thus it also plays a major role in the maintenance of defensive mechanism. Classification of drugs :.Antacids.Agents decreasing secretion of gastric acid . Agents protecting mucosal barrier.Agents eradicating helicobacter pylori Have bee

7、n used for centuries in the treatment of patients with acid-peptic disorders. Were the mainstay of treatment for acid-peptic disorders until the advent of H2-receptor antagonists and proton pump inhibitors. weak bases : Mg(OH)2 , Al(OH)3 , CaCO3 , NaHCO3actions: 1) prevent injury from H+ 2) neutrali

8、ze gastric acid reduce gastric acidity reduce peptic activity 3) protect face of ulcer( Mg2SiO8 Al(OH)3 ) Antacids NaHCO3+HCl Nacl+H2O+CO2 Mg2Si3O8+4HCl 2MgCl2+3SiO2 Al(OH)3+3HCl AlCl3+3H2O Mg(OH)2+HCl MgCl2+2H2O CaCO3+2HCl CaCl2+H2O+CO2 MgO+HCl MgCl2+H2O 表1、常用抗酸药的作用特点比较 NaHCO3 Mg2SiO8 Al(OH)3 Mg(OH

9、)2 CaCO3 MgO1g药中和0.1 120 150 250 210 200 500N的HCl ml数抗酸作用 弱快 弱慢 较强慢 较强快 较强快 最强作用持续时间 短 长 较长 较长 较长 较长 保护溃疡面 无 有 有 无 无 无收敛作用 无 无 有 无 有 无产生CO2 有 无 无 无 有 无嗳气引起便秘 无 无 有 无 有 无引起腹泻 无 有 无 有 无 有引起碱血症 有 无 无 无 无 无药物特点作用side reactions: disorder of gastrointestinal track diarrhea; constipation; belching打嗝打嗝; fla

10、tulence 肠胃胀气肠胃胀气; alkalemiaProglumide Drugs reducing secretion of gastric acid (1) H2-receptor antagonists (2) Antimuscarinic agents (3) Inhibitors of the proton pump (4) gastrin-receptor antagonistsCimetidine, Ranitidine, Famotidine , NizatidineActions Competitively block the binding of histamine t

11、o H2 receptor. Completely inhibit gastric acid secretion induced by histamine. characteristics: more effective than M-R antagonists;long duration; high rate of healing up; reboundProglumide Pharmacokinetics Absorption: p.o F=70% Distribution: widely Elimination: kidney ! Heptic microsomal enzyme inh