Simvastatin-amiodarone interaction resulting in rhabdomyolysis, azotemia, and possible hepatotoxicity.
OBJECTIVE
To describe the fifth reported instance, as of February 15, 2006, of a severe interaction between simvastatin and amiodarone and hypothesize inhibition of CYP3A4 as the major mechanism.


METHODS
A 72-year-old white man (178 cm, 77.2 kg) with diabetes mellitus, hyperlipidemia, hypertension, and mild azotemia was hospitalized on September 21, 2004, with thigh weakness, achiness, and dark urine for 7 days. Coronary artery bypass had been performed on July 7, 2004. Amiodarone 200 mg/day was started on July 10, and simvastatin 80 mg/day was initiated on August 13. Laboratory testing on the present admission included creatine kinase (CK) 19,620 U/L (reference range 60-224), blood urea nitrogen 50 mg/dL, creatinine 2.6 mg/dL, aspartate aminotransferase (AST) 912 U/L (30-60), alanine aminotransferase (ALT) 748 U/L (30-60), urine myoglobin 71,100 microg/L (<50), and serum myoglobin 13,877 microg/L (<110). Simvastatin and amiodarone were discontinued, and the patient was hydrated with forced alkaline diuresis. Thirteen days later, his CK was 323 U/L, creatinine 1.7 mg/dL, ALT 145 U/L, and AST 37 U/L.


CONCLUSIONS
Simvastatin is metabolized primarily by CYP3A4, and amiodarone is a recognized inhibitor of this enzyme. This may, therefore, account for the presumed drug interaction.


CONCLUSIONS
An objective causal assessment suggests that rhabdomyolysis, renal failure, and possibly hepatotoxicity were probably related to an amiodarone-simvastatin interaction.
Internal Medicine, Fairview Hospital and Cleveland Clinic Health System, Cleveland, OH 44111, USA.
Basma
B
Ricaurte
Amir
A
Guirguis
Harris C
HC
Taylor
Don
D
Zabriskie
D000368:Aged; D000638:Amiodarone / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D056486:Chemical and Drug Induced Liver Injury / Q000150:complications; D004347:Drug Interactions; D006801:Humans; D008297:Male; D012206:Rhabdomyolysis / Q000139:chemically induced* / Q000150:complications; D019821:Simvastatin / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D016896:Treatment Outcome; D014511:Uremia / Q000139:chemically induced* / Q000150:complications
D019821:Simvastatin; D000638:Amiodarone