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

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