Analgesia after operation. A controlled comparison of meptazinol, pentazocine and pethidine.

In a double-blind investigation of the efficacy on pain following abdominal or orthopaedic surgery, meptazinol 100 mg, a new hexahydroazepine derivative, was found to be equipotent with pentazocine 60 mg and pethidine 100 mg when given i.m. Analgesia was maximal 30-60 min after injection and was still present at the end of 2 h. The duration of action of meptazinol was estimated to be 4 h. Meptazinol produced less sedation and a greater sparing of lung function tests than did pethidine and pentazocine. When meptazinol or morphine was administered for further pain relief in a single-blind manner there was no evidence of patient preference for one drug or the other.