Voriconazole therapeutic drug monitoring in patients with invasive mycoses improves efficacy and safety outcomes.

BACKGROUND Voriconazole is the therapy of choice for aspergillosis and a new treatment option for candidiasis. Liver disease, age, genetic polymorphism of the cytochrome CYP2C19, and comedications influence voriconazole metabolism. Large variations in voriconazole pharmacokinetics may be associated with decreased efficacy or with toxicity. METHODS This study was conducted to assess the utility of measuring voriconazole blood levels with individualized dose adjustments. RESULTS A total of 181 measurements with high-pressure liquid chromatography were performed during 2388 treatment days in 52 patients. A large variability in voriconazole trough blood levels was observed, ranging from 5.5 mg/L (a level possibly associated with toxicity) in 31% of cases. Lack of response to therapy was more frequent in patients with voriconazole levels 1 mg/L (15 [12%] of 39 patients; P=.02). Blood levels >1 mg/L were reached after increasing the voriconazole dosage, with complete resolution of infection in all 6 cases. Among 16 patients with voriconazole trough blood levels >5.5 mg/L, 5 patients (31%) presented with an encephalopathy, including 4 patients who were treated intravenously with a median voriconazole dosage of 8 mg/kg per day, whereas none of the patients with levels <or=5.5 mg/L presented with neurological toxicity (P=.002). Comedication with omeprazole possibly contributed to voriconazole accumulation in 4 patients. In all cases, discontinuation of therapy resulted in prompt and complete neurological recovery. CONCLUSIONS Voriconazole therapeutic drug monitoring improves the efficacy and safety of therapy in severely ill patients with invasive mycoses.