Assessment of the Effective Dose of Isavuconazole, Itraconazole, Posaconazole, and Voriconazole to Achieve Goal Serum Concentrations in Pediatric Patients at a Single Center.

Abstract

Objective: The optimal dose for triazoles in pediatric patients may substantially vary given the dynamic changes in pharmacokinetics and pharmacodynamics, based on disease severity. Therapeutic drug monitoring has been a valuable tool to help guide management and avoid potential toxicities associated with treatment of invasive fungal infections (IFIs). Goal azole serum concentrations are based on specific drug, indication, and minimum inhibitory concentration when known. This study aimed to determine the optimal pediatric azole doses needed to achieve targeted serum concentrations of isavuconazole, itraconazole, posaconazole, and voriconazole.

Methods: This is a single center, retrospective chart review of pediatric patients who received isavuconazole, itraconazole, posaconazole, or voriconazole between January 1, 2011, and August 31, 2021.

Results: A total of 273 pediatric patients received isavuconazole, itraconazole, posaconazole, or voriconazole in the inpatient or outpatient setting during the study period. Of the 273 patients, only 122 met criteria for inclusion in the analysis. Eighty-three percent of patients reached a goal serum concentration. Patients younger than 12 years required a higher dose (mg/kg/day) to achieve goal serum concentrations. Patients who received an azole in the form of an oral tablet or intravenously were more likely to reach a goal concentration than those not receiving these formulations. Median time to goal concentration occurred at 20 days for isavuconazole, 34 days for itraconazole, 11 days for posaconazole, and 10 days for voriconazole.

Conclusions: Higher starting azole doses are needed to obtain goal concentrations quickly, especially for children younger than 12 years.