Pentazocine--naloxone: another "addiction-proof" drug of abuse.

Pentazocine, in combination with the antihistamine tripelennamine, was a popular drug of intravenous abuse in many large cities in the late 1970s and early 1980s. To stem the abuse of pentazocine, naloxone was added to the tablet. This would presumably allow oral activity, but naloxone would block the euphoria if the pills were injected. Abuse of pentazocine appears to have diminished, but we have recently treated three addicts who continued to inject pentazocine, despite its naloxone content. Two patients experienced no overall decrease in the drug-induced euphoria. The third patient became acutely psychotic with each injection. Hypotheses are advanced to explain these findings.