LOW-DOSE FAMOTIDINE AND RANITIDINE AS SINGLE POSTPRANDIAL DOSES - A 3-PERIOD PLACEBO-CONTROLLED COMPARATIVE TRIAL

Background: Low-dose H-2-receptor antagonists are available without pr escription for the self-medication of dyspepsia. Methods: To investiga te the relative abilities of low doses of famotidine and ranitidine to raise intragastric pH after a single post-prandial evening dose, 25 h ealthy volunteers completed a three-period cross-over trial of famotid ine 10 mg, ranitidine elixir 75 mg and placebo, A standard meal was gi ven 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, AKOVA) and 2.6 pH units/h foll owing ranitidine 75 mg (1.75; P < 0.001). The geometric mean area unde r 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 pl acebo, 2.7 following famotidine 10 mg (P < 0.05 by comparison with pla cebo) and 1.9 following ranitidine 75 mg (P < 0.05); comparison of med ian 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-do se 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 sig nificant difference between the active drugs. Conclusions: We conclude that both famotidine 10 mg and ranitidine 75 mg significantly raise i ntragastric 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.