EFFECTS OF OMEPRAZOLE, RANITIDINE, FAMOTIDINE AND LACEBO ON GASTRIC SECRETION IN PATIENTS NDERGOING ELECTIVE SURGERY

We have compared the effects of omeprazole, ranitidine, famotidineand placebo on gastric secretion in a double-blind study in110 patients undergoing elective surgery. Three hours beforeoperation, the patients received, orally, omeprazole 40 mg,ranitidine 150 mg, famotidine 40 mg or placebo. Gastric volumeand pH were measured immediately after induction of anaesthesia.Omeprazole, ranitidine and famotidine produced a significantincrease in gastric pH and a significant decrease in gastricvolume compared with placebo. When the effects of omeprazoleon gastric volume were compared with those of ranitidine andfamotidine, no significant difference was found, but omeprazolewas significantly less effective in increasing gastric pH. Thenumber of patients having a pH less than 2.5 and a volume greaterthan 0.4 mlkg^–1 were: none in the ranitidine group, one(3%) in the famotidine group, four (15%) in the omeprazole groupand six (23%) in the placebo group. We conclude that omeprazole40 mg given 2–4 h before surgery does not afford adequateprophylaxis for the acid aspiration syndrome.     

Comparison of the effects of famotidine and ranitidine on gastric secretion in patients undergoing elective surgery

A randomised double-blind comparison of oral famotidine and ranitidine given 2 hours before induction, on gastric secretion (volume and pH) was carried out on 93 patients undergoing elective surgery. Gastric contents were aspirated immediately after tracheal intubation. Famotidine significantly reduced the gastric volume, compared with the other groups, including ranitidine. Both famotidine and ranitidine significantly elevated gastric pH towards neutral, compared with the other groups. There was no significant difference between ranitidine and famotidine in respect of the pH. The patients premedicated with famotidine and ranitidine were well protected against Mendelson's syndrome, whereas 38% of patients from the other groups remained at risk.