Drug Interactions between Kisqali Femara Co-Pack and perflutren

GENERALLY AVOID: Perflutren lipid microsphere suspension (Definity)has been reported to cause prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In 221 study subjects who received ECG monitoring at various time points from 1 to 72 hours following administration of perflutren lipid microsphere bolus doses of up to 10 microL/kg, QTc prolongations of >30 msec were noted in 64 (29%) subjects. Forty-six out of these 64 subjects were further evaluated, and 18 (39%) were found to have associated cardiac rhythm changes. The effects of concomitant drugs were not studied. 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: Concomitant use of perflutren lipid microsphere suspension with other agents that can prolong the QT interval should be avoided in some cases. Please refer to the prescribing information for these drugs for more information. No data are available regarding the effect of perflutren protein-type A microsphere suspension (Optison) on the QT interval of the electrocardiogram.

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.