Versant-XR Drug Interactions

Beta-blockers (e.g., metoprolol): Increased AUC and C_max of metoprolol.
CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, erythromycin, cimetidine): May increase plasma felodipine levels (see Pharmacology: Pharmacokinetics under Actions).
Anticonvulsants and other enzyme inducers (e.g., phenytoin, carbamazepine, phenobarbital): May decrease plasma felodipine concentration.
Digoxin: The pharmacokinetics of digoxin in patients with heart failure were not significantly altered.
Tacrolimus: May increase tacrolimus blood concentration. When coadministered with felodipine, the tacrolimus blood concentration should be followed and the tacrolimus dose may need to be adjusted.
Grapefruit Juice: Taking grapefruit juice together with felodipine results in increased peak plasma levels and bioavailability possibly due to an interaction with flavonoids in the fruit juice. This interaction has been seen with other dihydropyridine calcium antagonists and represents a class effect. Thus, grapefruit juice should not be taken with felodipine.
Others: There were no clinically significant interactions when felodipine was given concomitantly with indomethacin or spironolactone in healthy subjects.
Felodipine does not affect plasma ciclosporin concentrations.
Felodipine does not appear to affect the unbound fraction of other extensively plasma protein bound drugs such as warfarin.