Drug interactions of Abemaciclib

CYP3A Inhibitors

Strong and moderate CYP3A4 inhibitors can clinically significantly increase the exposure of abemaciclib and its active metabolites, which may lead to increased toxicity.

Ketoconazole:

Avoid concurrent use of ketoconazole. Ketoconazole is expected to increase the AUC of abemaciclib by up to 16-fold.

Other Strong CYP3A Inhibitors:

For patients with a recommended starting dose of 200 mg twice daily or 150 mg twice daily, when coadministered with strong CYP3A inhibitors other than ketoconazole, reduce the abemaciclib dose to 100 mg twice daily.

For patients who have already had their dose reduced to 100 mg twice daily due to adverse reactions, further reduce the abemaciclib dose to 50 mg twice daily when coadministered with strong CYP3A inhibitors.

If a patient taking abemaciclib discontinues a strong CYP3A inhibitor, increase the abemaciclib dose (after 3-5 half-lives of the inhibitor) to the dose used prior to initiating the inhibitor.

Patients should avoid consuming grapefruit products.

Moderate CYP3A Inhibitors:

When coadministered with moderate CYP3A inhibitors, monitor for adverse reactions and consider reducing the abemaciclib dose in 50 mg increments as shown in Table 1 if necessary.

Strong and Moderate CYP3A Inducers

Concurrent use of strong or moderate CYP3A inducers decreases the plasma concentrations of abemaciclib and its active metabolites, which may lead to reduced efficacy. Avoid concurrent use of strong or moderate CYP3A inducers and consider alternative medications.

FDA，2025.02