Drug Interaction Report

MONITOR: Coadministration with blinatumomab may increase the plasma concentrations of drugs that are substrates of CYP450 isoenzymes. Initiation of blinatumomab treatment causes transient release of cytokines that may suppress CYP450 enzymes, although the potential for interaction has not been studied. Presumably, the highest drug-drug interaction risk would be during the first 9 days of the first cycle and the first 2 days of the second cycle.

MANAGEMENT: Caution is advised when blinatumomab is prescribed to patients receiving drugs that are metabolized by CYP450 isoenzymes, particularly those with a narrow therapeutic index such as carbamazepine, colchicine, cyclosporine, disopyramide, phenytoin, quinidine, theophylline, warfarin, macrolide immunosuppressants, vinca alkaloids, and some narcotic analgesics. Clinical and laboratory monitoring are recommended following the initiation of blinatumomab, and the individual dosage of the concomitant agents adjusted as needed.

ADJUST DOSING INTERVAL: Consumption of food has led to a 27% decrease in the bioavailability of orally administered tacrolimus.

MANAGEMENT: Tacrolimus should be administered at least one hour before or two hours after meals.

GENERALLY AVOID: Grapefruit juice has been reported to increase tacrolimus trough concentrations. Data are limited, but inhibition of the CYP450 enzyme system appears to be involved.

MANAGEMENT: The clinician may want to recommend that the patient avoid ingesting large amounts of grapefruit juice while taking tacrolimus.