The Dose-Response Effects of Oral Cimetidine on Gastric pH and Volume in Children

Abstract

The effects of preanesthetic oral cimetidine on gastric fluid pH and volume were studied in 97 infants and children. A dose-response curve was constructed using doses of 2.5, 5.0, 7.5 and 10 mg/kg. The ED50 of cimetidine that produces pH values > 2.5 was 3.0 mg/kg and the ED95 was 7.5 mg/kg. Cimetidine exponentially reduced gastric fluid volume. Cimetidine was most effective between 1-4 h after oral administration. In children who are at high risk of pulmonary aspiration, oral cimetidine, 7.5 mg/kg, should be given 1-3 h preoperatively to protect the lungs from the accidental aspiration of acidic gastric secretions.