Nocturnal intragastric acidity after over-the-counter doses of famotidine, ranitidine or placebo.

ABSTRACT

AIM: To compare the inhibitory effects of over-the-counter doses of famotidine or ranitidine on nocturnal intragastric acidity in a placebo-controlled study. METHODS: Twelve-hour intragastric acidity was measured simultaneously in 24 healthy subjects who ate a standard meal at 18.30 h and were dosed (at 19.30 h) with either famotidine 10 mg, ranitidine 75 mg or placebo in a balanced three-period crossover design. Five-millilitre aliquots of gastric juice were aspirated half-hourly 0-3 h post-dose, and then hourly until the end of the study. pH was measured with a glass electrode. Integrated pH (area under the curve (AUC) of the pH-time curve) was calculated for the intervals 0-12 h and 9-12 h post-dose. Statistical analysis was by ANOVA. RESULTS: In the 0-12 h post-dose period, when the 24 subjects were dosed with placebo, mean AUC was 2.12, increasing by 75% to 3.70 with famotidine (P < 0.001) and by 81% to 3.83 with ranitidine (P < 0.001). In the 9-12 h post-dose period, when the subjects were dosed with placebo, mean AUC was 2.13, increasing by 91% to 4.07 with famotidine (P < 0.001) and by 79% to 3.82 with ranitidine (P < 0.001). There was no significant difference between the pH-raising effects of famotidine and ranitidine in both periods. CONCLUSIONS: Famotidine and ranitidine in over-the-counter doses have a similar, sustained, effect on post-prandial nocturnal intragastric acidity in healthy subjects lasting up to 12 h after oral dosing.