Drug Interaction Report

GENERALLY AVOID: Coadministration with potent CYP450 3A4 inhibitors may increase the plasma concentrations and the risk of adverse effects of ribociclib, which is a substrate of the isoenzyme. In healthy subjects, administration of a single 400 mg dose of ribociclib with ritonavir (100 mg twice daily for 14 days), a potent CYP450 3A4 inhibitor, resulted in a 1.7-fold and 3.2-fold increase in ribociclib peak plasma concentration (Cmax) and systemic exposure (AUC), respectively, compared to ribociclib administered alone. In addition, administration of erythromycin, a moderate CYP450 3A4 inhibitor, is predicted to increase ribociclib Cmax and AUC by 1.3-fold and 1.9-fold, respectively. The risk of adverse effects such as infections, neutropenia, leucopenia, anemia, thrombocytopenia, nausea, vomiting, diarrhea, stomatitis, anorexia, alopecia, fatigue, headache, and abnormal liver function may be increased.

MANAGEMENT: Concomitant use of ribociclib with potent CYP450 3A4 inhibitors should generally be avoided. Alternative agents with no or minimal CYP450 3A4 inhibitory potential are recommended whenever possible. If no alternatives exist, the dose of ribociclib should be reduced to 400 mg once daily. Patients receiving concomitant treatment with a CYP450 3A4 inhibitor should be monitored for the development of ribociclib-related adverse effects. Following discontinuation of the potent CYP450 3A4 inhibitor, the ribociclib dosage should be returned (after at least 5 half-lives of the inhibitor) to that used prior to initiation of the inhibitor.

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.