Effects of omeprazole, ranitidine, famotidine and placebo on gastric secretion in patients undergoing elective surgery.

Abstract

We have compared the effects of omeprazole, ranitidine, famotidine and placebo on gastric secretion in a double-blind study in 110 patients undergoing elective surgery. Three hours before operation, the patients received, orally, omeprazole 40 mg, ranitidine 150 mg, famotidine 40 mg or placebo. Gastric volume and pH were measured immediately after induction of anaesthesia. Omeprazole, ranitidine and famotidine produced a significant increase in gastric pH and a significant decrease in gastric volume compared with placebo. When the effects of omeprazole on gastric volume were compared with those of ranitidine and famotidine, no significant difference was found, but omeprazole was significantly less effective in increasing gastric pH. The number of patients having a pH less than 2.5 and a volume greater than 0.4 ml kg-1 were: none in the ranitidine group, one (3%) in the famotidine group, four (15%) in the omeprazole group and six (23%) in the placebo group. We conclude that omeprazole 40 mg given 2-4 h before surgery does not afford adequate prophylaxis for the acid aspiration syndrome.