A double-blind comparison of morphine and buprenorphine in the prevention of pain after operation.

A double-blind, between-patient comparison has been made of the effects of morphine 10 mg i.v. and buprenorphine 0.3 mg i.v. on the prevention of pain after operation. The drugs were given by the anaesthetist at the end of the operation, and the onset and severity of pain were assessed by a trained nurse. Both drugs caused a significant delay in the appearance of severe pain when compared with the control group, but with buprenorphine the mean delay of 10.5 h was more than twice that of morphine. The only side-effect to occur more frequently after administration of the analgesics was drowsiness, the incidence being greater after buprenorphine than after morphine.