Daily gastric pH in controls and in duodenal ulcer patients: basal condition and response to treatment.

Gastric pH was monitored, by means of a computerized system, in healthy controls (C) and in patients with active duodenal ulcer (ADU) and inactive duodenal ulcer (IDU). The test was performed before treatment and during administration of a single dose of ranitidine 150 mg, cimetidine 400 mg, and pirenzepine 50 mg, in random sequence at 12-h intervals, (10 am, 10 pm). Under basal conditions, progressively lower median pH values were detected in ADU and IDU patients, compared with controls. A significant difference was found between C and ADU during daytime (1.38 vs. 0.85), nighttime (1.29 vs. 0.81), and 24 h (1.35 vs. 0.81) and between C and IDU during 24 h (1.35 vs. 1.11). However, no statistical difference was observed between patients with active and inactive ulcer disease. Administration of ranitidine and cimetidine significantly increased gastric pH during nighttime but not during daytime. Ranitidine, at the doses studied, proved to be more potent than cimetidine in suppressing gastric acidity. Gastric pH was unaffected by pirenzepine in most cases.