Inhibition of human gastric secretion by ICI 162,846--a new histamine H2-receptor antagonist.

The inhibitory effect of ICI 162,846, a new histamine H2-receptor antagonist, on gastric secretion of acid and pepsin was studied in 10 healthy male volunteers, aged 21-30 years. Single doses of 0.5, 1.0, 2.5 and 5.0 mg were given orally at 18:00 h. Overnight 12 h gastric secretion of acid was reduced by 69, 81, 91 and 95%, respectively. The inhibition of nocturnal output of pepsin was less than acid, with median decreases of 21, 42, 73 and 87%, respectively, of the output after administration of placebo. Intragastric concentration of acid, and values of intragastric pH, during the following 12 h of the day were not significantly affected by any of the doses of the drug. We conclude that ICI 162,846 is a powerful inhibitor of gastric secretion, with potential for use in the treatment of peptic diseases.