Drug Interaction Report

MONITOR: Coadministration with inhibitors of P-glycoprotein may increase the plasma concentrations of vismodegib, which has been shown in vitro to be a substrate of the efflux transporter. The potential for increased pharmacologic effects of vismodegib, including adverse effects such as muscle spasm, alopecia, dysgeusia/ageusia, weight loss, fatigue, nausea, vomiting, diarrhea, decreased appetite, constipation and arthralgia, should be considered.

MANAGEMENT: Caution is advised if vismodegib is used in combination with P-glycoprotein inhibitors.

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.