Therapeutic drug monitoring of flucytosine in a cardiac transplant patient receiving continuous veno‐venous hemofiltration and intermittent hemodialysis: A case report

Abstract Invasive candidiasis is one of the common infections in solid organ transplant recipients. Guidelines recommend echinocandins or liposomal amphotericin with consideration of flucytosine (5‐fluorocytosine; 5‐FC) as synergistic therapy for treatment of select deep‐seated Candida infections, including complex endovascular infections. Flucytosine undergoes extensive renal elimination; however, optimal dosing in patients with renal impairment, or those requiring renal replacement therapy (RRT), is not well‐established. We describe a case of a 60‐year old female who underwent orthotopic heart transplant complicated by Candida parapsilosis complex fungemia with mediastinitis and development of end‐stage renal disease requiring RRT. Flucytosine therapeutic drug monitoring was performed on continuous veno‐venous hemofiltration (CVVH) and intermittent hemodialysis (iHD) to guide appropriate dosing. Our results support 5‐FC doses of 25 mg/kg daily while undergoing CVVH with a low fluid replacement rate and 21 mg/kg post‐iHD or 17 mg/kg daily while receiving thrice weekly iHD.