Assessment of intragastric acidity in man: modern aspects, reproducibility of intragastric pH-monitoring, and pharmacodynamic results obtained with H2-receptor antagonists.

Unlike other methods for assessing intragastric pH or total acid output, the reproducibility of ambulatory pH-monitoring is excellent but is critically dependent on the electrode system and the recording device. In three double-blind randomized studies in normal volunteers the effects of different dosage regimens of roxatidine acetate were compared with placebo and ranitidine. Roxatidine acetate, 75 mg twice daily, raised median 24-h gastric pH from 1.6 to 3.2 and median nocturnal pH from 1.5 to 3.0 Roxatidine acetate, 150 mg at bedtime, raised median 24-h pH to 2.4 and nocturnal pH to 5.9. Roxatidine acetate, 150 mg at bedtime, was as effective as ranitidine, 300 mg at night, in raising median nocturnal pH. However, when drugs were taken after the evening meal, 150 mg roxatidine acetate was less potent than 300 mg ranitidine or 300 mg roxatidine acetate.