CYCLAZOCINE REVISITED

Recently synthesized compounds which have long-term mu antagonist acti vity and short-term kappa agonist effects prevent self-administration of cocaine and morphine in rats. Cyclazocine, a compound synthesized i n 1962 and studied in animals and man in the 1960's and in the early 1 970's is a mu antagonist in rats and man and is a potent kappa agonist in both species. It also prevents self-administration of cocaine and morphine in rats. Although it produces unpleasant side effects in man, subjects become tolerant to these side effects but not to the antagon istic actions of the drug after prolonged administration.