Drug Interactions between Kisqali Femara Co-Pack and siponimod

GENERALLY AVOID: Due to its significant bradycardic effects, the risk of QT prolongation and torsade de pointes arrhythmia may be increased during initiation of siponimod treatment in patients receiving drugs that prolong the QT interval. Siponimod can cause a decrease in heart rate during initiation of therapy that is apparent within an hour of the first dose, and the day 1 decline is maximal at approximately 3 to 4 hours. The maximal decrease in heart rate from baseline was seen between day 5 and 6. After day 6, heart rate starts increasing and reaches placebo levels within 10 days after treatment initiation. The highest daily post-dose decrease in absolute hourly mean heart rate is observed on day 1, with a decrease of 5 to 6 bpm. Following day 1, decreases in heart rate are less pronounced. Heart rates below 40 bpm were rarely observed. In controlled clinical trials, bradycardia (including sinus bradycardia and decreased heart rate) occurred in 6% of siponimod-treated patients compared to 3% of patients receiving placebo. Initiation of siponimod treatment has also resulted in transient AV conduction delays. First-degree AV block (prolonged PR interval on ECG) occurred in 5.1% of siponimod-treated patients and 1.9% of patients receiving placebo. Second-degree AV blocks, usually Mobitz type I (Wenckebach), have been observed at the time of siponimod initiation in less than 1.7% of patients. Bradycardia and conduction abnormalities were usually transient and asymptomatic, and resolved within the first 24 hours, but they occasionally required treatment with atropine. In a study evaluating the effect on QT interval of siponimod 2 or 10 mg at steady-state, siponimod treatment resulted in maximum prolongations of the QTc of 7.8 and 7.2 msec, respectively, with upper bounds of the 90% confidence interval of 9.93 and 9.72 msec, respectively. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Siponimod has not been studied in patients receiving drugs that can prolong the QT interval. Because bradycardia and AV block are recognized risk factors for QT prolongation and torsade de pointes arrhythmia, treatment with siponimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties. Advice from a cardiologist should be sought if treatment with siponimod is considered in patients on concurrent therapy with QT prolonging drugs with a known risk of torsades de pointes or drugs that slow heart rate or AV conduction.

MONITOR CLOSELY: Coadministration of siponimod with antineoplastic, immunosuppressive, or other immune-modulating therapies may increase the risk of unintended additive immunosuppressive effects. Siponimod causes reversible sequestration of lymphocytes in lymphoid tissues. When administered daily, siponimod produces a dose-dependent reduction in peripheral lymphocyte count to 20% to 30% of baseline values, which may increase the risk of infections. Life-threatening and rare fatal infections have occurred in association with siponimod. Decreased lymphocyte counts persist during chronic daily dosing and generally return to normal within 10 days after stopping the medication. Pharmacodynamic effects, such as decreased peripheral lymphocytes, may persist for 3 to 4 weeks after the last dose, and as a result, use of immunosuppressants during this time may also lead to additive immune effects.

MANAGEMENT: The safety and efficacy of siponimod in combination with antineoplastic, immunosuppressive, or immune-modulating agents have not been evaluated. Caution is advised during coadministration and for 3 to 4 weeks after the last dose of siponimod. When switching from drugs with prolonged immune effects to siponimod, the half-life and mode of action of these drugs must be considered to avoid unintended additive immunosuppressive effects while at the same time minimizing risk of disease reactivation.

MONITOR: Coadministration with ribociclib may increase the plasma concentrations and pharmacologic effects of drugs that are substrates of CYP450 3A4. The proposed mechanism is decreased clearance due to ribociclib-mediated inhibition of CYP450 3A4 metabolism. In healthy study subjects, administration of midazolam, a sensitive CYP450 3A4 substrate, with multiple 400 mg daily doses of ribociclib increased the midazolam peak plasma concentration (Cmax) and systemic exposure (AUC) by 2.1-fold and 3.8-fold, respectively, compared to midazolam administered alone. When given at a clinically relevant dose of 600 mg daily, ribociclib is predicted to increase midazolam Cmax and AUC by 2.4-fold and 5.2-fold, respectively.

MANAGEMENT: Caution is advised when ribociclib is used concomitantly with drugs that undergo metabolism by CYP450 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever ribociclib is added to or withdrawn from therapy.