Comparative study of the speed of acid‐suppressing effects of oral administration of cimetidine and famotidine

BACKGROUND AND AIM: H2 histamine receptor antagonists (H2RAs) are widely used in patients with acid-related diseases, and the onset of antisecretory activity of H2RAs is reported to be faster than that of proton pump inhibitors (PPIs). The aim of this study was to compare the rapidity of onset of antisecretory activity of cimetidine and famotidine when orally administered. METHODS: Fifteen healthy male Japanese volunteers (five H. pylori-positive and 10 H. pylori-negative) participated in a randomized cross-over study. All subjects were examined three times by ambulatory 6-h pH monitoring (from 17:30 to 23:30) with no medication or oral administration of 400 mg of cimetidine or 20 mg of famotidine. Drugs were administered at 19:30 after eating a standard meal, and plasma concentrations were also examined for 4 h periods. RESULTS: The plasma concentration of cimetidine increased rapidly after oral administration, while that of famotidine increased gradually. Intragastric pH was increased and percentage time with pH < 4.0 decreased significantly 2 h after administration of either cimetidine or famotidine. There was no statistically significant difference in acid-suppressing effect between cimetidine and famotidine during the short-term post-administration period. CONCLUSION: Rapidity of antisecretory activity did not differ between oral cimetidine and famotidine administered orally.