GASTRIC SECRETION INHIBITORS

GASTRIC SECRETION INHIBITORS act at some stage in the control process to inhibit the enzymic or gastric acid secretions of the stomach, with the latter being a major therapeutic target. The neuronal, hormonal and paracrine control of gastric acid secretion from the parietal cells of the gastric mucosa is complex. The pathways involved include acetylcholine via the parasympathetic innervation of the stomach, the hormone gastrin. the paracrine agent histamine and possibly the paracrine hormone gastrin-releasing peptide. Anticholinergic agents have not proved very valuable in the long-run, having a limited ability to reduce acid secretion at doses that can be tolerated in view of widespread side-effects. Some more recently developed agents show gastric-selectivity (they are Mrcholinoceptor-preferring ligands, which may be the reason for their selectivity), e.g. pirenzepine and telenzepine: see muscarinic cholinoceptor antagonists. Gastrin receptor antagonists and gastrin-releasing peptide antagonists have now been developed for experimental use, but it is not yet clear if either will be useful clinically. See BOMBESIN RECEPTOR ANTAGONISTS; CHOLECYSTOKININ RECEPTOR ANTAGONISTS. Histamine H2-receptor antagonists Read more […]

Heartburn

Heartburn (Gastroesophageal Reflux) In Pregnancy Heartburn is caused by a reflux of gastric acids into the lower esophagus, usually occurring after meals or when lying down. The gastric acids irritate the esophagus, causing a burning sensation behind the sternum that may extend into the neck and face, and may be accompanied by regurgitation, nausea, and hypersalivation. Inflammation and ulceration of the esophagus may result. Up to two-thirds of women experience heartburn during pregnancy. Only rarely it is an exacerbation of preexisting disease. Symptoms may begin as early as the first trimester and cease soon after birth. Most women first experience reflux symptoms after 5 months of gestation; however, many women report the onset of symptoms only when they become very bothersome, long after the symptoms actually began. The prevalence and severity of heartburn progressively increases during pregnancy. The exact causes(s) of reflux during pregnancy include relaxed lower esophageal tone, secondary to hormonal changes during pregnancy, particularly the influence of progesterone, and mechanical pressure of the growing uterus on the stomach which contributes to reflux of gastric acids into the esophagus. However, some Read more […]

ANTIULCEROGENIC AGENTS

ANTIULCEROGENIC AGENTS (or ulcer-healing drugs) are used to promote healing of ulceration of gastric and duodenal peptic ulcers. A number of classes of drugs may be used. See also gastric secretion inhibitors. First, the HISTAMINE H2-ANTAGONISTS are very effective and have considerable usage, e.g. cimetidine. famotidine, nizatidine and ranitidine. These agents decrease gastric acid secretion and promote healing and may be used to treat dyspepsia and oesophagitis of a number of etiologies. Acid production is also very effectively reduced by the newer agents, the proton pump inhibitors, e.g. omeprazole (see GASTRIC PROTON PUMP INHIBITORS). Anticholinergic drugs are only really suitable in the case of agents that show some gastric-selectivity, e.g. pirenzepine and telenzepine (see muscarinic cholinoceptor ANTAGONISTS). They work by reducing the secretion of peptic acid by the stomach mucosa. Some prostaglandin analogues are effective in protecting the mucosa, and are incorporated into some preparations of NSAIDs to offer concurrent protection (though they may cause unacceptable stimulation of the ileum), e.g. misoprostol. (see prostanoid receptor agonists) . Bismuth-containing antacid preparations have been Read more […]