[Analysis of voriconazole serum concentrations and safety profile in pediatric oncology patients].

BACKGROUND: Voriconazole (VCZ) serum drug levels (SDL) vary widely and are associated with increased mortality when they are below the therapeutic range for invasive aspergillosis (IA). AIM: To describe VCZ SDL in oncology pediatric patients in order to reach adequate concentrations for prophylaxis (≥ 0.5 mg/L) and treatment (≥ 1.0 y 2.0 mg/L) for IA and their relationship with toxicity. PATIENTS AND METHODS: Retrospective analysis of VCZ SDL and toxicities recorded in oncology pediatric patients between February 2013 and November 2014. The daily dosage and SDLs were analyzed according to administration route: intravenous (IV) and oral (PO), type of therapy (prophylaxis and treatment) and patient age (< 12 y ≥ 12 years old).
RESULTS: 112 through levels from 26 patients were analyzed and the average age was 9.3 years-old. The SDL obtained from the IV route were 43.7%. There were more SDL ≥ 0.5 mg/L and ≥ 1.0 mg/L with the IV route than the PO route (p < 0.05). Patients younger than 12-years-old received a higher dosage than those ≥ 12 years old (median 18.6 and 9.2 mg/kg/d, respectively, p < 0.05). To reach SDL ≥ 0,5 mg/L with the PO route, a dosage of 200 mg every 12 hours showed the best results for all patients (80-100% SDL ≥ 0.5 mg/L). With an IV dosage between 14 and 20 mg/kg/day in patients > 12-years-old, 80% of the SDL were ≥ 1 mg/L and ≥ 2 mg/L. In patients younger than 12-year-old, dosages between 8-30 mg/ kg/day showed similar results (50-63% of SDL ≥ 1 mg/L and 36-40% of SDL ≥ 2 mg/L). Eight patients (30.8%) presented an adverse drug reaction and no relationship with the SDL was found. Conclusión: A VCZ standard dosage of 200 mg every 12 hours PO showed the best results for IA prophylaxis in all patients. Patients younger than 12-years-old would require higher dosages than the doses used in this study to attain adequate SDL for IA treatment. No relation with SDL and adverse reactions was found.