Drug Interaction Report

GENERALLY AVOID: Concomitant use with multiple doses of vorasidenib may decrease the plasma concentrations of drugs that are substrates of CYP450 3A. Vorasidenib is predicted to be an inducer of CYP450 3A resulting in decreased plasma concentrations of agents that are metabolized by the isoenzyme. The interaction may be significant for sensitive CYP450 3A4 substrates or those that demonstrate a narrow therapeutic index. Clinical and pharmacokinetic data are currently lacking.

MANAGEMENT: Concomitant use of vorasidenib with substrates of CYP450 3A should be avoided due to the potential for reduced efficacy

GENERALLY AVOID: Theoretically, the coadministration with grapefruit juice may increase the plasma concentrations of pimozide. The mechanism is decreased clearance of pimozide due to inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The use of pimozide alone has been associated with dose-dependent prolongation of the QT interval. Although clinical data are lacking, this interaction may result in potentiation of the proarrhythmic effect of pimozide and consequently an increased risk of ventricular arrhythmias such as ventricular tachycardia and torsade de pointes. In addition, alcohol may potentiate some of the pharmacologic effects of pimozide. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: The manufacturer recommends avoiding grapefruit juice (and probably grapefruits) during therapy with pimozide. Patients should also be advised to avoid or limit consumption of alcohol.

GENERALLY AVOID: Due to induction of CYP450 1A2, the isoenzyme primarily responsible for the metabolic clearance of vorasidenib, smoking tobacco during treatment with vorasidenib may decrease its plasma concentrations and anti-tumor effect. Clinical and pharmacokinetic data are currently lacking.

MANAGEMENT: Patient should be advised to avoid smoking tobacco during treatment with vorasidenib because it may reduce efficacy of the therapy.