A double-blind clinical trial of the analgesic effects of R & S 218-M, a new potent analgesic for the relief or pain following abdominal surgery: comparison with morphine sulphate.

The analgesic effects of R & S 218-M, administered in doses of 0.56 mg/70 kg and 0.35 mg/70 kg, were compared with those of morphine sulphate 10.5 mg/70 kg for the relief of abdominal pain following surgery in healthy adults. The drugs were given as the first potent analgesic after operation and the subjects were interviewed at 30-min intervals until the pain became severe again. All the interviews were conducted by the one observer. R & S 218-M 0.56 mg/70 kg was as effective as morphine sulfate 10.5 mg/70 kg, while R & S 218-M 0.35 mg/70 kg was inferior. No evidence was found to support the claim that R & S 218-M causes less respiratory depression when compared with morphine sulphate.