Abstract

Nearly every powerful analgesic has been introduced with the claim that it does not cause dependence. Until about ten years ago it seemed unlikely that analgesia would be separated from this liability. Since then, two advances have led to considerable optimism: the development of critical methods of evaluating analgesia independently from addiction liability in man, and the discovery that nalorphine, a non-addicting morphine antagonist, was a powerful analgesic in man. Unfortunately nalorphine cannot be used clinically because it causes unpleasant mood changes and hallucinations. Pentazocine (Fortral - Bayer) is claimed to possess morphine-like analgesic properties, a low risk of inducing dependence and freedom from the unwanted effects of nalorphine.