Abstract
The effects of ranitidine on gastric secretion stimulated with gastric secretagogues were studied in 6 Heidenhain pouch dogs (both male beagle and mongrel). Cimetidine was used as a reference drug. Either histamine 2HCl (40μg/kg), pentagastrin (2μg/kg) or carbachol (2μg/kg) was given intramuscularly, every 15min for 120min. Gastric juice was collected at each 15min interval and analyzed for volume, acidity and pepsin activity. Either ranitidine (0.3, 1 or 10mg/kg) or cimetidine (1or 10mg/kg), packed in a gelatin capsule, was given orally 60 min before the initial injection of each stimulant. Both ranitidine and cimetidine dosedependently inhibited histamine- and pentagastrin-stimulated gastric secretion (volume, acid and pepsin output) These agents also inhibited the carbachol-stimulated secretion, but the antisecretory effects were weak as compared with their effects on histamine- and pentagastrin-stimulated secretions. The antisecretory effect of ranitidine on each stimulant is roughly 2 to 17 times more potent than cimetidine on the basis of ED50 (antisecretory dose which inhibits gastric secretion by 50%). The antisecretory effect of ranitidine (10mg/kg) on pentagastrin-stimulated secretion was observed even 10hr after its oral administration.
