The pharmacology of 20681-S and 20682-S, 6-oxo-N-cyclopropylmethylmorphinans, as narcotic antagonist analgesics.

It has been demonstrated that L-3hydroxy-6-oxo-N-cyclopropylmethylmorphinan methansulfonate (20681-S) and L-3,14-dihydroxy-6-oxo-N-cyclopropylmethylmorphinan methansulfonate (20682-S), have antinociceptive and narcotic antagonistic properties. In the rodent antinociceptive test, the action of 20681-S was more potent and of longer duration than that of morphine and of cyclazocine after subcutaneous or oral administration. The antinociceptive effect of 20682-S ranked between that of morphine and that of pentazocine in the mouse acetic acid-writhing test. Both compounds possessed potent narcotic antagonistic activities, 20682-S being more active than naloxone and oxilorphan and 20681-S being equipotent with cyclazocine. The latent side effects (respiratory depression and fall in blood pressure) and the acute toxicity of 20681-S and 20682-S, were less than those of reference narcotic antagonists or of narcotic antagonist analgesics.