[Effectiveness of cimetidine, pirenzepine and synthetic secretin on stimulated gastric acid secretion]. / Untersuchungen zur Effektivität von Cimetidin, Pirenzepin und synthetischem Sekretin auf die stimulierte Magensäuresekretion.

Two possibilities of an inhibition of gastric acid secretion are compared in regard to effectiveness and side effects. Combined i.v. bolus injection of 0.3 mg/kg cimetidine caused almost complete inhibition of peptone-stimulated acid secretion in normal volunteers and duodenal ulcer patients-radomized and double blind investigated-to the same extent as high dose secretin (3 CU/kg/h i.v. infusion) in normal volunteers. Postprandial gastrin was unchanged by combined drug application, but was suppressed by secretin. Temporary blurred vision, dry mouth, and signifiant increase of serum prolactin were side effects of the drug combination, whereas secretin caused dose-dependent diarrhoea, increaded diuresis and elecvation of serum lipase, trypsin, and sodium. Inhibition of acid secretion by combination of the antimuscarinic drug pirenzepine with the H2-receptor blocking substances cimetidine was almost complete, i.e. more effective than the combination of classic anticholinergics with H2-blockers tested so far. Inhibition of acid secretion by secretin was dose-dependent; the dosage clinically applied so far (10 CU/kg s.c. and 0.5 CU/kg/h i.v.) had the smallest effect. In spite of first favourable results with secretin in bleeding mucosal lesions, the observed side effects cast doubt on its broad clinical applicability. A controlled clinical trial of the combination of cimetidine plus pirenzepine as prophylaxis of bleeding from mucosal lesions in risk patients seems to be indicated.

Interactions of cimetidine and pirenzepine on peptone-stimulated gastric acid secretion in man.

Combinations of H2-receptor antagonists and classical anticholinergics inhibit stimulated gastric acid secretion more than either drug alone. In double blind, placebo controlled, randomised studies we have compared the effects of single and combined intravenous bolus injections of cimetidine and pirenzepine on peptone-stimulated acid secretion and serum gastrin in man. Combined injection of 3.0 mg/kg cimetidine and 0.3 mg/kg pirenzepine suppressed stimulated acid secretion significantly more than either drug alone, and by 90% in healthy volunteers (n = 8) and patients with duodenal ulcer (n = 5). Side-effects (prolactin stimulation, blurred vision) were diminished by reducing the combined dosages to 1.5 mg/kg cimetidine, to 0.075 and 0.15 mg/kg pirenzepine in another series (n = 10). Postprandial gastrin was not affected by any combination. Combination of cimetidine and pirenzepine suppress food-stimulated gastric secretion more effectively than combination of H2-blockers with classical anticholinergics. Pirenzepine--unlike classical anticholinergics--may distinguish between different subclasses of muscarinic receptors and have a more selective antimuscarinic action. Its interaction with H2-receptor antagonists on parietal cell function seems to be synergistic. Such a combination could be of advantage in patients with gastrinoma, in patients with ulcers and hypersecretion resistant to single drug treatment, and in critically ill patients as prophylaxis of stress ulcer bleeding.