Drug Interaction Report

MONITOR: Coadministration with olutasidenib may decrease the plasma concentrations of drugs that are substrates of CYP450 3A4. Based on in vitro studies, olutasidenib may increase clearance via induction of CYP450 3A4, resulting in decreased plasma concentrations of agents that are metabolized by the isoenzyme. Clinical and pharmacokinetic data are currently lacking.

MANAGEMENT: Caution is advised if olutasidenib is used concomitantly with drugs that are substrates of CYP450 3A4, particularly sensitive substrates or those with a narrow therapeutic range. The prescribing information for olutasidenib recommends avoiding coadministration with CYP450 3A4 substrates for which minimal concentration changes may lead to therapeutic failure. If coadministration is required, clinical and laboratory monitoring may be appropriate whenever olutasidenib is added to or withdrawn from therapy. The prescribing information for concomitant medications should be consulted to assess the benefits versus risks of coadministration and for any dosage adjustments that may be required.

ADJUST DOSING INTERVAL: Coadministration with a high-fat meal may increase the plasma concentrations of olutasidenib. According to the product labeling, administration of a single 150 mg dose with a high-fat meal (approximately 800 to 1000 calories, with approximately 50% of those calories from fat) increased olutasidenib peak plasma concentration (Cmax) and systemic exposure (AUC) by 191% and 83%, respectively, in healthy subjects.

MANAGEMENT: Olutasidenib should be administered at about the same time each day, on an empty stomach at least 1 hour before or 2 hours after a meal.

Grapefruit juice may delay the gastrointestinal absorption of clarithromycin but does not appear to affect the overall extent of absorption or inhibit the metabolism of clarithromycin. The mechanism of interaction is unknown but may be related to competition for intestinal CYP450 3A4 and/or absorptive sites. In an open-label, randomized, crossover study consisting of 12 healthy subjects, coadministration with grapefruit juice increased the time to reach peak plasma concentration (Tmax) of both clarithromycin and 14-hydroxyclarithromycin (the active metabolite) by 80% and 104%, respectively, compared to water. Other pharmacokinetic parameters were not significantly altered. This interaction is unlikely to be of clinical significance.