Inhibition of food-stimulated acid secretion (intragastric titration) by roxatidine acetate. Dose-response study.

In 10 healthy male volunteers a dose-response study was carried out with roxatidine acetate, 75, 150, 300, and 600 mg, and placebo on food-stimulated gastric acid secretion (intragastric titration (IGT]. The design of the study, with drug intake 150 min before starting IGT, enabled stable inhibition over the 90-min observation period of the test. Cumulative secretory results showed a dose-related acid secretion inhibition (67% for 75 mg; 87.6% for 150 mg; 98.8% for 300 mg; 99.6% for 600 mg). The results were statistically significantly different from placebo and from each other, except for 300 mg versus 600 mg. With a Lineweaver-Burk plot, the ED50 was 41 mg and r = 0.98. Peak concentrations of roxatidine were observed either at T 150 or T 180. Significant correlation (r = 0.7; p less than 0.001) was obtained for the percentage inhibition with 75 mg and 150 mg together versus peak concentrations. Antisecretory potency with the IGT model applied to normal subjects appears to be of the same order for roxatidine acetate and for ranitidine.