Intramuscular buprenorphine for pain relief after abdominal surgery: a comparison between on-demand and prophylactic administration.

The efficacy of intramuscular (i.m.) buprenorphine, given either at the end of anaesthesia or to treat established pain was investigated on 60 patients scheduled for major abdominal surgery receiving isoflurane anaesthesia. During skin closure (1st injection), patients were given either i.m. buprenorphine 0.3 mg or i.m. saline. Pain was assessed every hour in the post-anaesthetic care unit by the patient using a numerical rating scale. Patients were given 0.3 mg of i.m. buprenorphine (2nd injection) on request. The study was completed when a 3rd injection of i.m. buprenorphine 0.3 mg was required. The overall impressions of patients, nurses and doctors were recorded on a scale ranging from 1 to 5 at the end of the study. The interval between the 1st and 2nd injection was significantly longer (P < 0.001) following administration of buprenorphine (5 h 18 min) than saline (1 h 3 min). Mean pain scores were significantly lower after buprenorphine compared to saline (P < 0.01). There was no significant difference in duration of action or mean pain scores following buprenorphine given either at wound closure or on first demand. However, overall impressions recorded at the end of the study were significantly better when buprenorphine was given preventatively. Prophylactic buprenorphine proved to be a suitable analgesic after an inhalational anaesthesia.