Sulfamethoxazole-Trimethoprim-Induced Rhabdomyolysis in an Immunocompetent Patient: A Case Report

Sulfamethoxazole-trimethoprim (TMP-SMX)-induced rhabdomyolysis is a rare complication of a commonly used antibiotic. This is a case report of a 43-year old immunocompetent African American woman with a history of depression and chronic alcohol consumption who presented to the emergency department (ED) with worsening bilateral leg pain. Before presentation, the patient was prescribed a twice daily dose of TMP-SMX for a urinary tract infection. The patient reported the development of intensifying leg pain after taking five doses of TMP-SMX. On presentation to the ED she was hemodynamically stable, afebrile, and leg pain intensity 10 out of 10. The patient admitted to daily alcohol consumption and taking vortioxetine 10 mg per day for treatment of depression. Initial labs drawn in the ED showed an elevated creatine kinase (CK) of 26,231 U/L and a normal serum creatinine (SCr) of 1 mg/dL. Through patient history and laboratory tests, common causes of rhabdomyolysis were ruled out. Treatment was initiated with IV fluids plus thiamine and folic acid supplementation, TMP-SMX was discontinued, and vortioxetine 10 mg per day was continued until hospital day five. The patient began to show improvement in lower extremity pain and tenderness and was discharged on hospital day eight with minimal residual leg pain and a CK of 2809 U/L. This case report presents only the third incidence of an immunocompetent patient developing TMP-SMX-induced rhabdomyolysis. This case highlights an opportunity for a pharmacist’s intervention and the need for future research to determine risk factors of TMP-SMX-induced rhabdomyolysis in immunocompetent patients.