Liquid Chromatography-Tandem Mass Spectrometry-Based Therapeutic Monitoring of Plasma Atovaquone Concentrations in Pediatric Patients

Atovaquone is an FDA-approved antiparasitic and antifungal therapeutic that is currently used as a prophylactic agent to prevent Pneumocystis carinii pneumonia (PCP) infections in acute myeloid leukemia (AML) patients after receiving hematopoietic stem cell transplantation (HSCT). Recent studies have shown that atovaquone has shown potential as an anticancer agent. The high variability in atovaquone bioavailability prompts the need for therapeutic drug monitoring, especially in pediatric patients. The goal of our study was to develop and validate the performance of an assay to quantify atovaquone plasma concentrations collected from pediatric cancer patients. Briefly, an organic-based solvent system is used to precipitate protein and extract the atovaquone content from each patient-derived plasma sample. After completing a second stage of sample dilution (5000-fold overall), a 2 μL volume of the plasma extract is analyzed using the liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based bioanalytical method described.