Canadian Journal of Anesthesia, Vol 42, 793-796, Copyright © 1995 by Canadian Anesthesiologists' Society

ARTICLES

Ranitidine suspension or famotidine resoriblette and gastric fluid volume and pH

M Oikkonen, O Erkola and R Collan
Department of Anaesthesia, Maria Hospital, Helsinki, Finland.

We studied the effect of two new formulations of H2-receptor antagonists on gastric fluid pH and volume. Forty-five healthy, elective adult in-patients in three study groups, 15 in each, were premedicated using oral diazepam 10 mg with 100 ml of a dose of water soluble suspension of ranitidine 300 mg with sodium citrate/bicarbonate, or a resoriblette of famotidine 40 mg, or placebo. Gastric fluid samples were obtained by blind aspiration after anaesthesia induction, 50-70 min from premedication, and again 90 min from premedication. After a mean period of 60 min from ingestion the patients medicated with H2-antagonists had higher gastric juice pH than those in the control group (1.5 (1.1-6.3), median (range)) (P ] 0.0001) for ranitidine (6.8 (4.1-7.8)), P < 0.01 for famotidine (3.9 (1.5-7.6)); P < 0.05 ranitidine vs famotidine). Recovered volumes were similar for the groups (median 3-4 ml, range 0-50 ml). None of the H2 patients had pH < 3.5 and volume > or = 0.3 ml.kg-1 (P < 0.05 vs placebo). In second aspirations, taken 90 min from premedication, the group differences from control in pH persisted. Famotidine patients had the lowest volumes (P < 0.05 vs controls); yet one famotidine patient had a pH < 2.5 and volume > or = 0.3 ml.kg-1. It is concluded that, at the moment of oral anxiolytic premedication, ranitidine-buffer suspension effectively reduced gastric juice acidity, whereas famotidine resoriblette failed to increase reliably gastric pH in 50-90 min.