24-hour control of intragastric acidity by cimetidine in duodenal-ulcer patients.

The effects of two dose regimens of cimetidine on 24 h intragastric acidity were investigated in six patients with duodenal ulcer. They received placebo capsules on the first day and cimetidine on the second day. Cimetidine 0-8 g/day decreased 24 h mean H+ activity by 55% but 1-6 g/day decreased it by 67%, the difference being due to a greater nocturnal decrease in the high-dose group. Intragastric pH remained below 2-0 for much of the treatment day but similar values were found in four post-vagotomy patients. Cimetidine 0-8-1-6 g/day results in a decrease of intragastric acidity that is compatible with successful medical treatment of duodenal ulceration.