Twice daily nizatidine or ranitidine is superior to once daily dosing in elevating 24 h intragastric pH in patients with duodenal ulcer disease.

The present study was performed in six asymptomatic patients with a history of resistant duodenal ulcers in whom 24 h intragastric pH, gastric juice pepsin and PGE2 concentrations, as well as serum gastrin concentrations, were measured. We wanted to compare the effects on these parameters of a single night time (q.h.s.) dose of nizatidine 300 mg (N1), nizatidine 300 mg b.i.d. (N2), ranitidine 300 mg q.h.s. (R1) or ranitidine 300 mg b.i.d. (R2) compared with placebo (P). During the night (22.00-08.00 h), all treatments gave a higher mean pH than P, but during the day (08.00-22.00 h) the mean pH was higher than P only for patients administered R2 and N2. Doubling the dose of nizatidine (N2 vs N1) or ranitidine (R2 vs R1) increased the mean daytime pH, but had no effect on night time pH. The daytime pepsin concentration was unaffected by H2-receptor antagonists, while night time pepsin was lower with R1 and R2, but not with N1 or N2. The night time gastrin concentration was unaffected by H2-receptor antagonists; doubling the dose of the H2-receptor antagonist (R2 vs R1 and N2 vs N1) increased daytime gastrin concentration. During the night, each treatment increased PGE2 concentration by at least six-fold compared with P. Thus, where it is therapeutically indicated to achieve greater suppression of acid secretion, doubling the total daily dose by dosing with twice daily versus once daily night time nizatidine or ranitidine is efficacious.