The effect of ranitidine 300 mg at night, ranitidine 300 mg twice daily and placebo on 24-h intragastric pH and 24-h plasma gastrin in healthy subjects

Objective: The aim of this study was to examine the acute effects of ranitidine 300 mg at night and ranitidine 300 mg twice daily on 24-h intragastric acidity and 24-h plasma gastrin levels in a double blind, randomized, placebo-controlled study. Patients and methods: Twelve healthy male subjects were studied. Intragastric acidity was measured by radiotelemetry and 24-h plasma gastrin was derived from hourly blood samples. Both regimens were very effective in reducing median 24-h intragastric acidity, but the twice daily regimen was significantly better than dosing at night (80.5 compared with 71.8%, P < 0.05) by virtue of the greater reduction in daytime acidity (75.6 compared with 45.4%, P < 0.01). There was no significant difference in the effect on nocturnal acidity (95.6 compared with 93.2%). The median integrated 24-h plasma gastrin value increased from 774 pmolh/l on placebo to 1047 pmolh/l on ranitidine 300 mg at night (P < 0.01) and to 1180 pmolh/l on ranitidine 300 mg twice daily (P < 0.01). There was no significant difference in the effect of the two ranitidine regimens on the integrated plasma gastrin levels. Conclusion: Acute treatment with ranitidine 300 mg twice daily results in superior control of 24-h intragastric acidity compared with ranitidine 300 mg at night without a significant increase in plasma gastrin levels.