Effect: Voriconazole may increase the plasma concentrations of naproxen.
Clinical management: Caution should be exercised upon coadministration of these drugs. Monitor for increased naproxen toxicity and adjust dose if necessary.
Probable mechanism: Inhibition of the cytochrome P450 (CYP) 2C9-mediated biotransformation by voriconazole.
Summary: Although not studied for naproxen, coadministration of voriconazole and ibuprofen/diclofenac (both CYP2C9 substrates) in two seperate single-dose drug interaction studies resulted in increased AUC and Cmax for both NSAIDs. Coadministration with the CYP2C9 substrate naproxen could result in similar effects. Hence, frequent monitoring for NSAID toxicities during coadministration and possible dose adjustment of naproxen may be necessary.
- SPC Naproxen
QT effectVoriconazole: Conditional QT risk
Substantial evidence reports that this drug causes QT prolongation and has a risk of TdP, but only under certain known conditions (e.g. excessive dose, drug interaction, etc.).