Gastrointestinal Implications of Voriconazole Exposure

Voriconazole clearance in children (2-12 years old) is 3-fold higher and bioavailability is one half of adult values. An important gap in knowledge exists that explain the mechanisms that result in higher clearance and lower bioavailability of voriconazole and places children at a substantial risk for sub-therapeutic concentrations and treatment failures. Preliminary data suggests that intestinal first-pass metabolism is responsible for the lower bioavailability in children, but not in adults. By inhibiting intestinal metabolism with grapefruit juice, the extent of the effect of intestinal first-pass metabolism on voriconazole pharmacokinetics can be determined. Inpatient children at the Children's Hospital of Philadelphia who are receiving oral voriconazole as standard of care will be enrolled in an open label, cross-over clinical trial to monitor plasma voriconazole levels after voriconazole administration with and without grapefruit juice to inhibit intestinal metabolism of voriconazole. The proposed research will elucidate the role of intestinal metabolism in the reduced oral bioavailability of voriconazole in children, which can be incorporated into a model simulation to guide accurate dosing.