Table 4: Effect of Other Drugs on Voriconazole Levels

Table 4. Effect of Other Drugs on Voriconazole Levels

Drug/Drug Class	Voriconazole Levels	Recommendations for voriconazole dose adjustments
Rifampin/Rifabutin (CYP450 Induction)	Significantly reduced	CONTRAINDICATED
Carbamazepine (Tegretol®) (CYP450 Induction)	Likely to result in significant reduction	CONTRAINDICATED
Long-acting barbiturates (CYP450 Induction)	Likely to result in significant reduction	CONTRAINDICATED
Phenytoin (Dilantin®) (CYP450 Induction)	Significantly reduced	Increase maintenance dose to 5mg/kg IV Q 12 hrs or 400 mg PO Q 12 hrs (If < 40 kg; 200 mg PO Q 12 hrs)
HIV Protease Inhibitors (PIs) (CYP450 Induction)	In-vivo studies showed no effect of indinavir (Crixivan®) on voriconazole; In-vitro studies show potential for interaction	No dose adjustment needed with indinavir. Monitor for adverse effects or toxicity when given with other PIs.
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) (CYP450 Induction or Inhibition)	Potential for inhibition or induction exists	Monitor for adverse effects and toxicity of voriconazole or monitor for clinical efficacy of voriconazole