The effects of 300 mg ranitidine at night, twice daily and four times daily on intragastric acidity in normal subjects.

The aim of this study was to compare to placebo the effects of 300 mg ranitidine nocte, b.d. and q.d. on intragastric acidity. The study was performed on healthy male subjects and intragastric acidity measured by radiotelemetry. All active treatments significantly decreased 24-hr acidity, with a median suppression of 61.0% with 300 mg ranitidine nocte, 77.7% with 300 mg b.d. and 78.0% with 300 mg q.d.s. There was no significant difference between the effects of two higher dose regimens; although the 300 mg q.d.s. suppressed daytime acidity more than 300 mg b.d. (88.9% vs. 77.8%), it suppressed nocturnal acidity less effectively (65.5%) than either 300 mg nocte (92.9%) or 300 mg b.d. (90.0%). These data suggest that only modest additional therapeutic acid inhibition can be achieved by increasing the dose of ranitidine above 600 mg daily.