Pentazocine fibrous myopathy: report of two cases and literature review.

Two patients are described in whom the analgesic, pentazocine (Talwin), injected intramuscularly over long periods of time, resulted in a fibrous myopathy of the injected muscles. Although early testing of pentazocine indicated a low abuse potential and no skin or muscle complications, reports of such abuse and complications have since appeared in the literature, a review of which is included.