Efficacy of the extradural administration of lofentanil, buprenorphine or saline in the management of postoperative pain. A double-blind study.

Sixty postoperative orthopaedic patients were randomly assigned to three equal groups to study, in a double-blind fashion, the analgesic effects, durations of action and side effects of the extradural administration of lofentanil 5 micrograms, buprenorphine 0.3 mg or physiological saline. No systemic analgesics were given before, during or after surgery, and all the patients had operations on the lower extremities under extradural analgesia (lignocaine and bupivacaine). Eleven millilitre of the test drug was injected at T12-L1 as soon as pain occurred in the postoperative period. We observed a long duration of action and a marked analgesic effect with lofentanil, a shorter duration of action and less pain suppression with buprenorphine and a rather marked placebo effect after saline. The only side effect noticed in this study was drowsiness in three patients in the lofentanil group and in two patients in the buprenorphine group.