Prolonged gastric pH monitoring in responder and nonresponder duodenal ulcer patients: response to placebo and to H2-blocker administration.

We evaluated the circadian pattern of gastric acidity by prolonged intraluminal pHmetry in 15 "responder" and 10 "nonresponder" duodenal ulcer patients after nocturnal administration of placebo, ranitidine, and famotidine. Acidity was measured during predefined periods under the different drug regimens in the two groups of subjects, and a comparison was performed both within and between groups. With placebo, significantly lower median 24-h pH values were detected in patients with resistant ulcer than in responders (1.13 versus 1.63). On the contrary, no statistical difference was detected between the two groups during any time of day after administration of either ranitidine or famotidine. Within each group, no significant difference was noted between the two different H2-blockers. Thus, our data suggest that patients with resistant duodenal ulcer display an increased gastric acidity in control conditions but a "normal" response to administration of antisecretory drugs.