Extradural morphine for pain after surgery.

The effects of 10 mg of morphine sulphate given either extradurally or i.m. for the relief of pain after operation were compared in two randomized double-blind trials in patients undergoing major gynaecological surgery. In the first trial when morphine was given with the local anaesthetic before surgery, extradural administration resulted in significantly longer lasting analgesia: mean 707 min compared with 371 min (i.m.). In the second trial in patients complaining of pain after operation, extradural morphine had a slower onset of action, but longer duration of action compared with i.m. morphine, although the differences were not statistically significant. In this group extradural morphine often failed to provide useful analgesia. The extradural group received significantly less additional morphine (6.75 mg) than did the i.m. group (18.75 mg) in the following 24 h.