Drug Interaction Report

MONITOR: Coadministration with modafinil (the racemate) or armodafinil (the R-enantiomer) may decrease the plasma concentrations of delavirdine due to induction of CYP450 3A4 metabolism. Conversely, delavirdine may increase the plasma concentrations of modafinil due to inhibition of CYP450 3A4. The clinical significance is unknown. Modafinil and armodafinil are modest CYP450 3A4 inducers in vitro, while delavirdine is considered a potent inhibitor of the isoenzyme.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with decreased or subtherapeutic antiretroviral drug levels, caution is advised if modafinil or armodafinil must be used in patients treated with delavirdine. Clinical monitoring for altered effects of both drugs may be appropriate following addition or withdrawal of one or the other drug.

Administration with food may delay the absorption of modafinil (the racemate) and armodafinil (the R-enantiomer) without significantly affecting their overall bioavailability. According to the product labeling, modafinil's absorption may be delayed by approximately one hour if taken with food. Similarly, the time to reach peak plasma concentration (Tmax) of armodafinil may be delayed by approximately 2 to 4 hours in the fed state.