INHIBITION OF BASAL AND STIMULATED GASTRIC H+ AND PEPSIN SECRETION IN DUODENAL-ULCER PATIENTS BY METIAMIDE, AN H-2 HISTAMINE ANTAGONIST

Metiamide was given orally in 1 dose of 200 mg in 23 studies in patients with duodenal ulcer, 4 in the basal state, 11 during histamine infusion, and 8 before insulin hypoglycemia stimulation. In the latter 8 patients insulin was given at another time without metiamide. In 17 studies acid secretion was suppressed by metiamide up to 75% in the basal state, 53% after histamine and 80% after insulin. Pepsin secretion was reduced to the same extent as H+ in the histamine studies but not in the basal (57%) or insulin (44%) studies, so that in the latter pepsinlacid ratios were 3-fold greater than in controls. Blood levels of metiamide were measured in 17 studies. In 10 out of 11 who showed inhibition of 40% or more, peak blood levels of metiamide were 0.45-1.25 .mu.g/ml. In 5 of 6 who did not show inhibition, blood levels were 0.05-0.4 .mu.g/ml; in the 6th it was 0.8 .mu.g/ml. A critical blood level for suppression of basal or stimulated secretion appears to be .apprx. 0.45 .mu.g/ml.