Drug Interaction Report

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations of romidepsin, which is primarily metabolized by the isoenzyme. In patients with advanced cancer, administration of romidepsin 8 mg/m2 (4-hour infusion) with ketoconazole resulted in a 10% increase in romidepsin peak plasma concentration (Cmax) and 25% increase in systemic exposure (AUC) compared to romidepsin administered alone. The potential for increased risk of hematologic toxicities such as anemia, leukopenia, and thrombocytopenia as well as electrocardiographic changes such as QT interval prolongation and T-wave and ST-segment changes should be considered.

MANAGEMENT: Caution is advised when romidepsin is used with potent CYP450 3A4 inhibitors. Patients should have complete blood cell counts, electrocardiograms, and serum electrolyte levels performed at baseline and regular intervals as recommended in the product labeling. Patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

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.