Low-dose famotidine and ranitidine as single post-prandial doses: a three-period placebo-controlled comparative trial

Background: Low-dose H₂-receptor antagonists are available without prescription for the self-medication of dyspepsia.

Methods: To investigate the relative abilities of low doses of famotidine and ranitidine to raise intragastric pH after a single post-prandial evening dose, 25 healthy volunteers completed a three-period cross-over trial of famotidine 10 mg, ranitidine elixir 75 mg and placebo. A standard meal was given at 18.30 h and drug or placebo at 19.30 h to subjects fasted for 5.5 h. Intragastric pH was recorded with nasogastric electrodes from 18.00 to 07.30 h by GastrograpH II recorder.

Results: The geometric mean area under the pH–time curve for the 5–9 h post-dose period was 1.49 pH units/h following placebo, 3.43 pH units/h following famotidine 10 mg (agent/placebo ratio 2.3; P< 0.001, ANOVA) and 2.6 pH units/h following ranitidine 75 mg (1.75; P<0.001). The geometric mean area under the pH–time curve ratio of famotidine 10 mg to ranitidine 75 mg was 1.32 (P<0.016). Median pH over the 5–9 h period was 1.1 following placebo, 2.7 following famotidine 10 mg (P<0.05 by comparison with placebo) and 1.9 following ranitidine 75 mg (P<0.05); comparison of median pH showed no significant difference between the active drugs. The percentage of pH values greater than 3.0 for the period 0–12 h post-dose was 9.7% following placebo, 30.0% following famotidine 10 mg (P<0.05) and 24.9% following ranitidine 75 mg (P<0.05); there was no significant difference between the active drugs.

Conclusions: We conclude that both famotidine 10 mg and ranitidine 75 mg significantly raise intragastric pH when given as single post-prandial doses. Famotidine 10 mg may have a greater effect than ranitidine elixir 75 mg over the 5–9-h period after dosing.