Dosage adjustment of fluconazole during continuous renal replacement therapy (CAVH, CVVH, CAVHD, CVVHD)

Abstract

Continuous arterio-venous haemofiltration (CAVH), continuous veno- venous haemofiltration (CVVH), continuous arteriovenous haemodialysis (CAVHD) and continuous veno-venous haemodialysis (CVVHD) are increasingly used in patients with acute renal failure (ARF). The elimination rate of fluconazole varies considerably depending on the procedure used. (In Germany, fluconazole is approved for the treatment of life-threatening fungal infections caused by Candida spp. and Cryptococcus neoformans at a dosage of up to 800 mg day-1.) The elimination rate of fluconazole by CVVHD depends on the combined dialysate/ultrafiltrate flow rate, but is much higher than achieved with CVVH and intermittent dialysis, with a fluconazole clearance in patients with CVVHD 21 h-1 exceeding the values of healthy persons. To achieve therapeutic plasma levels during continuous renal replacement therapy, the same loading dose as in patients without renal failure should be administered, followed by a maintenance dose that is adjusted for anuric patients by multiplying by a factor that takes into account the extracorporeal elimination of the absorbed dose (CAVH, CVVH x 2.2, ultrafiltrate flow 0.51 h-1; CAVHD, CVVHD x 3.8, combined dialysate/ultrafiltrate flow 1.51 h-1). Despite the broad therapeutic margin of fluconazole, drug monitoring is recommended to achieve therapeutic drug levels in life-threatening indications because there have been only a few investigations of this, all involving relatively low dosages (up to 200 mg day-1).