Drug Interaction Report

MONITOR: Coadministration with pitolisant may decrease the plasma concentrations of drugs that are primarily metabolized by CYP450 3A4. Pitolisant is a borderline/weak inducer of CYP450 3A4. When studied with midazolam, a probe substrate for CYP450 3A4, pitolisant was found to reduce midazolam peak plasma concentration (Cmax) and systemic exposure (AUC) by less than 25%.

MANAGEMENT: Caution is advised when pitolisant is used in combination with sensitive CYP450 3A4 substrates. Clinical and laboratory monitoring may be appropriate whenever pitolisant is added to or withdrawn from therapy, and dosage adjustments made if necessary. It may be advisable to avoid concomitant use of pitolisant and CYP450 3A4 substrates with a narrow therapeutic index, if possible.

ADJUST DOSE: Smoking tobacco may decrease the steady-state systemic exposure of istradefylline by 38% to 54%.

MANAGEMENT: The possibility of reduced therapeutic effects of istradefylline should be considered in smokers. The manufacturer recommends an istradefylline dosage of 40 mg once daily in patients who smoke 20 or more cigarettes (or the equivalent amount of another tobacco product) per day.