Pharmacodynamics of bolus famotidine versus infused cimetidine, ranitidine, and famotidine.

A four-way crossover pilot study was conducted to compare the pharmacodynamic response of intermittent famotidine (20 mg every 12 hr) to continuous infusions of cimetidine (1200 mg/24 hr), ranitidine (150 mg/24 hr), and famotidine (40 mg/24 hr) in six normal male volunteers. Intragastric pH was monitored continuously for 24 hours. Comparisons included percent time during the 24-hour period that gastric pH was greater than pH 4.0, and pH 5.0, and also for the steady-state period of each regimen (12-24 hr). Although no statistically significant difference was observed for any of these comparisons, a clinically relevant trend was observed. In crossover experiments, famotidine intermittent infusions provided gastric pH readings above 4.0 and 5.0 for a longer duration than any of the continuous infusion regimens. Famotidine intermittent infusion regimens (20 mg every 12 hr) are at least equivalent to continuous infusions of cimetidine, ranitidine, and famotidine. Based on these findings, comparative studies in an appropriate critical care population would be beneficial, but any such studies must use a crossover design because of the even higher degree of intersubject variance in pH control. For this reason, the normal volunteer crossover model used here may provide important comparative information for the various regimens used in suppression of gastric acidity.