Drug Interaction Report

MONITOR: Based on in vitro data, coadministration with delavirdine may increase the plasma concentrations of voriconazole. The mechanism is delavirdine inhibition of CYP450 2C9 and 2C19, the isoenzymes responsible for the metabolic clearance of voriconazole. Conversely, voriconazole may also increase the plasma concentrations of delavirdine via inhibition of CYP450 3A4.

MANAGEMENT: Caution is advised if voriconazole must be used concomitantly with delavirdine. Patients should be frequently monitored for drug toxicity during coadministration of these drugs, and the dosage(s) adjusted accordingly.

ADJUST DOSING INTERVAL: Food reduces the oral absorption and bioavailability of voriconazole. According to the product labeling, administration of multiple doses of voriconazole with high-fat meals decreased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 34% and 24%, respectively, when the drug is administered as a tablet, and by 58% and 37%, respectively, when administered as the oral suspension.

MANAGEMENT: To ensure maximal oral absorption, voriconazole tablets and oral suspension should be taken at least one hour before or after a meal.