Comparison of oral slow release morphine (MST) with intramuscular morphine for premedication.

Oral morphine sulphate slow-release (MST) 40 mg and intramuscular morphine sulphate 10 mg, each administered with intramuscular atropine 0.6 mg, were compared in a randomised double-blind trial as premedication agents in 30 patients undergoing abdominal hysterectomy. Both formulations produced sedation but no anxiolysis in the anaesthetic room, as measured by 10 cm, horizontal linear analogue scales. There was no significant difference between the preparations in terms of postoperative pain, recorded either by the linear analogue scales or using a patient questionnaire. The usage of analgesics and anti-emetics postoperatively was comparable in both groups.