Muscle fibre necrosis induced by intramuscular injection of drugs.

A number of amphiphilic and lipid-soluble drugs of heterogeneous pharmacological properties, when injected into rat anterior tibial muscles, induced acute muscle fibre necrosis. The myotoxic agents were: penicillin, cloxacillin, phenobarbital, haloperidol, diazepam, hydantoin, metoclopramide, pentazocine and chlorpromazine. The regenerative process, studied using the latter three medications, showed rapid regeneration, complete within 3 weeks. Injection of the water-soluble drugs aminophylline, tranexamic acid and vitamins B6 and B12 produced no tissue damage. The pathogenesis of muscle fibre necrosis is suggested to involve direct damage to cell membranes by lipid soluble drugs.