title: Subtherapeutic voriconazole concentrations associated with concomitant dexamethasone: case report and review of the literature.
abstract: OBJECTIVE
  Voriconazole has significant drug interactions due to metabolism by CYP enzymes. Subtherapeutic voriconazole concentrations associated with concomitant dexamethasone are not well described.
  
  
  METHODS
  An 84-year-old male was started on voriconazole for a fungal brain abscess. He was readmitted due to clinical failure thought to be the result of subtherapeutic voriconazole concentrations. Dexamethasone was identified as a potential cause due to its induction of CYP enzymes. This interaction was substantiated by sequential troughs that demonstrated a rise in voriconazole concentrations as dexamethasone was tapered off.
  
  
  CONCLUSIONS
  Therapeutic drug monitoring for patients on voriconazole and dexamethasone is essential to prevent suboptimal clinical outcomes.
authors.affiliation: Pharmacy, University of Kentucky Healthcare, Lexington, KY, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Wallace
authors.affiliation: UMass Memorial Health Care, Worcester, MA, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Filipek
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: La Hoz
authors.affiliation: Pharmacy, Wake Forest Baptist Health, Winston-Salem, NC, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Williamson
keywords: dexamethasone; drug-drug interaction; fungal brain abscess; therapeutic drug monitoring; voriconazole