Drug Interactions between fosamprenavir and vorasidenib

ADJUST DOSING INTERVAL: Food may reduce the systemic bioavailability of amprenavir from fosamprenavir oral suspension. The mechanism of interaction has not been described. According to the product labeling, administration of fosamprenavir oral suspension (1400 mg single dose) with a high-fat meal (967 kcal, 67 g fat, 33 g protein, 58 g carbohydrate) reduced amprenavir peak plasma concentration (Cmax) by 46% and systemic exposure (AUC) by 28% compared to administration in a fasted state. The time to reach peak plasma level (Tmax) was delayed by 0.72 hours. In contrast, the same high-fat meal did not affect the pharmacokinetics of amprenavir from fosamprenavir tablets.

MANAGEMENT: Fosamprenavir suspension should be administered on an empty stomach in adults, but with food in pediatric patients to aid palatability and compliance. If emesis occurs within 30 minutes after dosing the suspension, the dose should be repeated. Fosamprenavir tablets may be taken with or without food.

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.