Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR CLOSELY: Coadministration with potent inducers of CYP450 3A4 and/or P-glycoprotein may significantly decrease the plasma concentrations and pharmacologic effects of tacrolimus. The mechanism probably involves reduced absorption as well as accelerated clearance of tacrolimus due to induction of both intestinal P-glycoprotein drug efflux transporter and hepatic/intestinal CYP450 3A4 isoenzymes. In a study of six healthy volunteers, a potent inducer of CYP450 3A4 and P-gp, rifampin (600 mg daily for 18 days) increased the average clearance of tacrolimus (0.1 mg/kg orally and 0.025 mg/kg/4 hours intravenously) by 47% and decreased its oral bioavailability from 14% to 7%. There have been case reports of transplant patients whose tacrolimus blood levels dropped significantly or became subtherapeutic as early as two days following the initiation of rifampin, subsequently requiring discontinuation of rifampin or substantial increases (up to ten-fold over several months) in tacrolimus dosage.

MANAGEMENT: Given the risk of organ rejection associated with inadequate immunosuppressant levels, caution is advised if tacrolimus must be coadministered with potent inducers of CYP450 3A4 and/or P-gp. Tacrolimus blood levels should be closely monitored and the dosage adjusted accordingly, particularly following initiation or discontinuation of inducer therapy in patients who are stabilized on their anti-rejection regimen.

You should preferably avoid consumption of grapefruit and grapefruit juice while taking encorafenib. Grapefruit and grapefruit juice can significantly increase the blood levels of encorafenib. This may increase the risk of serious side effects such as bleeding complications, eye and vision problems, liver problems, irregular heart rhythm, and development of new skin cancers. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Tacrolimus should be taken on a consistent schedule before or after you eat at the same times each day. Grapefruit and grapefruit juice may increase the amount of tacrolimus in your body. This can lead to potentially dangerous side effects and should be avoided. If you are already consuming grapefruit products, do not increase or decrease the amount of these products in your diet without first talking to your doctor.

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