Voriconazole and Dexamethasone Drug Interaction in a Premature Neonate.

Neonatal invasive fungal infections (IFI) from Aspergillus species are increasing in frequency. While voriconazole remains the antifungal of choice for treatment in many patient populations, several pharmacokinetic challenges affect dosing of voriconazole in premature neonates. Further complicating voriconazole use are the unknown implications of drug interactions in the preterm population. We report a case of voriconazole use in a neonate for the treatment of cutaneous Aspergillosis with variable serum voriconazole concentrations, reflecting a suspected drug interaction with dexamethasone. Serum voriconazole concentrations were initially subtherapeutic despite multiple dose escalations, then unexpectedly increased to supratherapeutic range as a concomitant dexamethasone course was tapered. Re-initiation of voriconazole after discontinuation of dexamethasone resulted in supratherapeutic concentrations that were discordant from previous serum concentrations on the same voriconazole dose while receiving dexamethasone. This is the first report of a potential drug interaction between voriconazole and a corticosteroid in a preterm neonate, highlighting the importance of drug interactions in voriconazole dosing evaluation and monitoring in this population.