Effects of metoclopramide and ranitidine on gastric fluid volume and its acidity

The effects of metoclopramide 10 mg and ranitidine 150 mg on gastric fluid volume and its pH are studied when given orally either alone or in combination, 3 hours before induction of anaesthesia in adult surgical patients. The study shows that metoclopramide causes reduction of gastric fluid volume but does not elevate its pH. Ranitidine elevates the pH of gastric fluid satisfactorily in all cases, but reduces the gastric volume below the critical level only in 50% cases. A combination of the said two drugs offered most satisfactory protection against acid aspiration syndrome almost in all cases. This regime seems to be superior to either ranitidine or metoclopramide alone in order to reduce the risk factors for aspiration of gastric contents.