The gastrin-receptor antagonist L-365,260 inhibits stimulated acid secretion in humans.

We investigated the effect of a novel gastrin-cholecystokinin-B receptor antagonist, L-365,260 [(3R)-3(N'-3-methylphenyl)ureido)-1,3-dihydro-5-phenyl- 2H-1,4-benzodiazepin-2-one], on gastric acid secretion in humans. In a double-blind, four-period crossover study, eight subjects received single oral doses of placebo or of 2.5, 10, or 50 mg L-365,260, followed by an intravenous infusion of pentagastrin at doses of 0.05, 0.4, and 2 micrograms/kg/hr for successive 30-minute periods. L-365,260 caused a dose-dependent inhibition of pentagastrin-stimulated gastric acid secretion. A single oral dose of 50 mg L-365,260 produced 50% inhibition of the gastric acid output response to pentagastrin (0.4 micrograms/kg/hr) when the mean (+/- SD) plasma L-365,260 concentration was 502 +/- 108 ng/ml. Plasma L-365,260 concentrations (all doses combined) and the inhibition of gastric acid output were correlated with a correlation coefficient of r = 0.45 (p < 0.05). Single oral doses of L-365,260 up to 50 mg did not inhibit basal gastric acid output or alter plasma gastrin concentrations. L-365,260 was well tolerated at oral doses up to 50 mg. These findings show that L-365,260 is an orally active antagonist at gastrin-cholecystokinin-B receptors in humans.