Twenty-four-hour intragastric acidity in duodenal ulcer patients during dosing with placebo, and 150 mg ranitidine twice or four times daily.

Twenty-four-hour intragastric acidity was measured in 10 patients with a past history of duodenal ulcer on the fourth day of dosing with placebo, and either 150 mg ranitidine given twice or four times daily. The order of the treatments was randomized and a double-blind design was employed. Ranitidine (150 mg) b.d. decreased median integrated 24-h intragastric acidity by 65.1%, nocturnal acidity by 89.1%, and daytime acidity by 54.6% (all P less than 0.01 compared to placebo). The corresponding decreases with 150 mg ranitidine q.d.s. were 62.3, 89.9 and 48.8%, respectively (all P less than 0.01) compared to placebo). There were no significant differences between the two dosage regimens of ranitidine (P greater than 0.05). This study shows that giving extra doses of 150 mg ranitidine during the day does not increase the degree of suppression of intragastric acidity.