tailieunhanh - CLINICAL PHARMACOLOGY 2003 (PART 32)

Approximately one-third of the population in Western societies experiences regular dyspepsia, although more than half selfmedicate with over-the-counter antacid preparations and do not seek medical advice. Up to 50% of those who do will have demonstrable pathology, most commonly gastro-oesophageal reflux or peptic ulceration. The remainder, in whom no abnormality is found, are diagnosed as having nonulcer pathophysiology and treatment differ for each of these three conditions. | -- SECTION GASTRO- INTESTINAL SYSTEM This page intentionally left blank SECTION Oesophagus stomach and duodenum SYNOPSIS Approximately one-third of the population in Western societies experiences regular dyspepsia although more than half selfmedicate with over-the-counter antacid preparations and do not seek medical advice. Up to 50 of those who do will have demonstrable pathology most commonly gastro-oesophageal reflux or peptic ulceration. The remainder in whom no abnormality is found are diagnosed as having nonulcer pathophysiology and treatment differ for each of these three conditions. Drugs for peptic ulcer Neutralisation of secreted acid Reduction of acid secretion Enhancing mucosal resistance Eradication of Helicobacter pylori NSAIDs and the stomach Gastro-oesophageal reflux and vomiting Antiemesis and prokinetic drugs Treatment of various forms of vomiting Peptic ulcer occurs when there is an imbalance between the damaging effects of gastric acid and pepsin and the defence mechanisms which protect the gastric and duodenal mucosa from these substances Fig. . The exact mechanisms are still poorly understood. A major cause of peptic ulcer is use of nonsteroidal anti-inflammatory drugs NSAIDs particularly in the elderly. Treatment of peptic ulceration has traditionally centred around measures to neutralise gastric acid to inhibit its secretion or to enhance mucosal defences. More recently recognition of the central role of Helicobacter pylori has revolutionised treatment. Smoking is a major environmental factor and patients who smoke should be advised to stop. ACID SECRETION BYTHE STOMACH Gastric acid is secreted by the parietal cells in gastric mucosa. The basolateral membranes of these cells contain receptors for the three main stimulants of acid secretion namely gastrin from antral G cells histamine from enterochromaffin-like cells and acetylcholine from vagal efferents . The action Protective Aggressive Fig. Factors involved in .