The magnitude of nocturnal acid suppression by ranitidine 300 mg given at 18.00 hours.

Ranitidine 300 mg given at 18.00 hours in 5 patients with CVA resulted in 99.5 per cent acid suppression for 12 hours. Intragastric pH of 4 or greater was obtained in only 58 per cent of the 12-hour period. An early evening dose of ranitidine is probably more effective and dosage reduction may be applicable for the healing of duodenal ulcers. However, ranitidine as given in this study is probably not adequate for stress ulcer prophylaxis.