Interactions between nuvigil(armodafinil) and Calan sr (verapamil)
verapamil and armodafinil (Moderate Drug-Drug)
MONITOR: Coadministration with modafinil (the racemate) or armodafinil (the R-enantiomer) may decrease the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme. Modafinil and armodafinil are modest inducers of CYP450 3A4, and pharmacokinetic studies suggest that their effects may be primarily intestinal rather than hepatic. Thus, clinically significant interactions would most likely be expected with drugs that have low oral bioavailability due to significant intestinal CYP450 3A4-mediated first-pass metabolism (e.g., buspirone, cyclosporine, lovastatin, midazolam, saquinavir, simvastatin, sirolimus, tacrolimus, triazolam, calcium channel blockers). Chronic administration of 250 mg doses of armodafinil has been shown to reduce midazolam systemic exposure (AUC) by 32% and 17% after single oral (5 mg) and intravenous (2 mg) doses, respectively. Similar reductions in plasma concentrations were also observed for cyclosporine, ethinyl estradiol, and triazolam during coadministration of modafinil.
MANAGEMENT: Pharmacologic response to these drugs may be altered and should be monitored more closely whenever modafinil or armodafinil is added to or withdrawn from therapy. Dosage adjustments may be required if an interaction is suspected.
