Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR: Coadministration with treosulfan may increase the plasma concentrations of drugs that are substrates of CYP450 3A4, 2C19, and/or the efflux transporter P-glycoprotein (P-gp). The proposed mechanism is decreased clearance due to inhibition of these routes of elimination due to treosulfan. According to physiologically-based pharmacokinetic modeling, treosulfan is predicted to be a weak to moderate CYP450 3A4 inhibitor and weak inhibitor of CYP450 2C19, with negligible inhibitory effects on P-gp. However, according to the manufacturer, in vitro studies were unable to exclude potential drug-drug interactions with high plasma concentrations of treosulfan and CYP450 3A4, 2C19, and/or P-gp substrates.

MANAGEMENT: Caution is recommended if treosulfan is coadministered with substrates of CYP450 3A4, 2C19, and/or P-gp, particularly those with a narrow therapeutic range. Some authorities advise that if concomitant use is required, the dosage of these substrates should be administered either 2 hours before or 8 hours after administration of the treosulfan infusion. The prescribing information of the substrates may be consulted for potential dose reductions.

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.