Scarpignato, C., R. Tramacere, and A. Peuetta: Effect of famotidine and ranitidine on gastric secretion and emptying in the rat. Drug Dev. Res. 11:37-43, 1987.The antisecretory and gastric motor effects of the new H2-receptor antagonist famotidine (MK-208) were compared with those of ranitidine in the rat. The Shay rat preparation (5 hr) was used for studying gastric secretion. Gastric motility was assessed by measuring gastric emptying of a liquid meal. Both compounds inhibited acid secretion in a dosedependent fashion. Calculated EDs0 values were 0.80 and 6.84 mgakg-' for famotidine and ranitidine, respectively. Therefore, in this animal model, famotidine was about 9 times more potent than ranitidine. The duration of antisecretory action however, was virtually the same for both drugs. The effect of the two drugs -administered at equiactive antisecretory doses -on gastric emptying was different. Indeed, ranitidine significantly accelerated emptying rate, whereas famotidine was ineffective. The results of the present investigation demonstrate that famotidine is a potent and selective antisecretory compound.

The effect of caerulein (100 ng/kg/h × 1 h) on basal as well as on thyrotropin-releasing hormone (TRH)-stimulated prolactin and thyroid-stimulating hormone (TSH) secretion was studied in healthy male volunteers. The peptide did not change the basal levels of prolactin and TSH. However, during the infusion of caerulein, prolactin response to TRH was significantly increased whereas the TSH response was decreased. These data, showing an action of caerulein (a frog peptide which mimics the biological actions of cholecystokinin) on prolactin and TSH release, suggest that cholecystokinin may be involved in the physiological control of human pituitary secretion.

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