Rhabdomyolysis requiring emergency dialysis as a consequence of simultaneous administration of simvastatin and clarithromycin

Abstract

Iatrogenic complications from polypharmacy have significantly increased over the past decade and clinicians and pharmacists must remain aware of potentially dangerous drug interactions 1–3. Our case is a reminder of the potential for significant patient harm from drug interactions when additional medication that is seemingly innocuous is prescribed in addition to a patient’s regular long-term medications. Our case also highlights the diagnosis and management of rhabdomyolysis and acute kidney injury. A 75-year-old Caucasian male presented to the emergency department with nausea, bilateral calf tenderness and a reduced urine output. Creatinine Kinase (CK) levels demonstrated severe rhabdomyolysis and the patient’s creatinine was significantly elevated with a concurrent metabolic acidosis requiring urgent renal replacement therapy in the intensive care unit (ICU). He was recently prescribed clarithromycin 500mg twice daily as part of Helicobacter pylori eradication therapy in addition to his regular combination therapy of simvastatin 80 mg and ezetimibe 10 mg daily dose. Statins may cause dose dependent Statin Associated Myopathies (SAMs) such as myositis and rhabdomyolysis and are metabolised by the hepatic cytochrome P450 (CYP450) 3A4 enzyme4,5. Clarithromycin is a potent CYP450 3A4 hepatic enzyme inhibitor that leads to significantly elevated plasma levels of statin medications, increasing the risk of SAMs4,6–8. Our patient responded to the cessation of the offending medications and initiation of continuous renal replacement therapy. This case demonstrates the dangerous side effects and interactions of commonly prescribed medications.