Abuse of pentazocine-naloxone combination.

The combination of pentazocine hydrochloride and tripelennamine hydrochloride (T's and blues) has been abused as a heroin substitute. In response to this abuse, the formulation of pentazocine has been changed to include naloxone hydrochloride, a short-acting narcotic antagonist, in the tablet (Talwin Nx). Two cases of abuse of the new pentazocine and naloxone formulation along with tripelennamine are reported. Potential reasons for the failure of naloxone to block the effects of pentazocine are discussed.