Effect of i.v. metoclopramide on gastric emptying after opioid premedication

Metoclopramide was given i.m. or i.v. to patients who had been given an opioid premedication, and the effects on gastric emptying assessed. Forty patients were allocated randomly to one of four treatment groups: group 1, oral diazepam 10 mg; group 2, i.m. morphine 10 mg; group 3, i.m. morphine 10 mg and i.v. metoclopramide 10 mg; group 4, i.m. morphine 10 mg and i.m. metoclopramide 10 mg. Gastric emptying was estimated from the absorption of oral paracetamol. I.v. metoclopramide antagonized the reduction in paracetamol absorption caused by morphine, whereas i.m. metoclopramide did not. This finding may be of importance in anaesthesia for emergencies.