A COMPARATIVE-STUDY OF THE INTERACTION BETWEEN ANTACID AND H-2-RECEPTOR ANTAGONISTS

The influence of concomitant antacid administration on the relative bi oavailability of the H-2-receptor antagonists cimetidine, famotidine, nizatidine and ranitidine, was investigated in a panel of 21 healthy, adult male volunteers in an eight-way crossover trial. Administration with antacid reduced the bioavailability of all agents tested. The red uction in area under the serum concentration-time curve (AUC) was grea test for cimetidine (23%) and ranitidine (26%) and least for nizatidin e (12%) and famotidine (19%). Reductions in peak serum concentration ( C(max)) followed a similar pattern. The times of peak serum concentrat ions were not affected by antacid. Comparison of the relative bioavail ability among all drugs tested showed no statistically significant dif ferences in the effect of antacid administration on these agents. Howe ver, a high degree of intersubject variability was observed.