Controlled comparison of I.M. morphine and buprenorphine for analgesia after abdominal surgery

In a double-blind randomized non-crossover trial 47 patients received either morphine or buprenorphine by regular i.m. injection for 24 h after abdominal surgery. The two drugs were equally effective as analgesics at the doses used. Five in the buprenorphine group and none in the morphine group were excluded because of respiratory depression. Four of these had received opiates during operation. The remainder of the buprenorphine group developed progressively slower respiration rates after 12 h. The results indicate that buprenorphine has a synergistic respiratory depressant effect with fentanyl and phenoperidine and may have a cumulative effect when given regularly on a 6-hourly regimen.