Drug Interactions between finasteride and tacrolimus

GENERALLY AVOID: Grapefruit and/or grapefruit juice may increase the plasma concentrations of tacrolimus. The proposed mechanism for the interaction is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. Although clinical data are lacking, this interaction may result in increased risk of serious adverse reactions such as nephro- and neurotoxicity, as well as other adverse effects associated with tacrolimus such as malignancies, infections, diabetes, hyperkalemia, hypertension, and QT prolongation.

GENERALLY AVOID: Alcohol may modify the rate of tacrolimus release from extended release formulations, thereby potentially increasing the risk of serious adverse reactions.

ADJUST DOSING INTERVAL: Coadministration with food decreases the rate and extent of tacrolimus absorption. This effect is greatest after a high-fat meal.

MANAGEMENT: Patients should avoid consumption of food or drink containing grapefruit during treatment with tacrolimus. Concomitant use of tacrolimus, especially extended release formulations, with alcohol should also be avoided. Tacrolimus extended release formulations should be administered on an empty stomach, at least 1 hour before or 2 hours after a meal, and tacrolimus immediate release formulations should be taken consistently every day with or without food.