Myopathy in long-term AZT therapy: clinical, electrophysiological and biopsy study in 67 HIV+ subjects.

The occurrence of muscular pathologies in AZT treated subjects has been evaluated in 67 HIV seropositive outpatients (56 AZT-treated and 11 untreated controls) in a neurological clinical and paraclinical follow-up study. Standard electromyographic and electrodiagnostic examinations, together with muscle enzyme determination, were performed in every subject, and periodically repeated at fixed intervals; in 11 patients a muscle biopsy sample was also obtained. An AZT-related myopathy was diagnosed in 8 biopsied cases; 9 more patients were considered to have AZT myopathy on clinical, EMG and ex juvantibus criteria. Statistical analysis showed that treatment duration was more relevant to the development of the myopathy than AZT dosage, though an individual predisposition could not be excluded, at least in a small number of cases. The risk of developing a toxic myopathy will therefore have to be considered when evaluating long-term effects of AZT therapy.