Zidovudine (AZT, 3-azido-3'-deoxythymidine) may cause a myopathy in some HIV-positive patients.
Clinical and laboratory features:
(1) proximal muscle weakness
(2) fatigue
(3) myalgias
(4) elevated serum CK concentrations
(5) muscle biopsy shows ragged red fibers with abnormal mitochondria
(6) reversal on discontinuation of AZT therapy
The myopathy may be accompanied by evidence of damage to cardiac myocytes.
The diagnosis is supported if there is no other alternative explanation for a myopathy.
The cause of the myopathy is uncertain. It may be due to:
(1) an interaction between the HIV virus and the AZT.
(2) impaired replication of the mitochondrial DNA.
(3) dysfunction of the respiratory chain in the mitochondria.
(4) impaired protein synthesis within mitochrondria
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Specialty: Surgery, orthopedic, Pharmacology, clinical
