Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of ribociclib, which is a substrate of the isoenzyme. Physiologically-based pharmacokinetic simulations (PBPK) suggest that a moderate CYP450 3A4 inducer, efavirenz, may decrease ribociclib Cmax and AUC by 37% and 60%, respectively. However, data with less potent CYP450 3A4 inducers are limited.

MANAGEMENT: The potential for diminished therapeutic effects of ribociclib should be considered when prescribed with inducers of CYP450 3A4, particularly moderate inducers including efavirenz and nevirapine. Pharmacologic effects of ribociclib should be monitored more closely whenever an inducer is added to or withdrawn from therapy. Alternative treatment may be required if an interaction is suspected.

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.

GENERALLY AVOID: Pomegranates and grapefruit may increase the systemic exposure to ribociclib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in these fruits. Increased exposure to ribociclib may increase the risk of adverse effects such as infections, neutropenia, leukopenia, anemia, thrombocytopenia, anorexia, nausea, vomiting, diarrhea, stomatitis, alopecia, fatigue, headache, and abnormal liver function may be increased.

MANAGEMENT: Patients receiving ribociclib should avoid consumption of pomegranates or pomegranate juice and grapefruit or grapefruit juice during treatment.