Drug Interactions between cinacalcet and fosamprenavir

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.

ADJUST DOSING INTERVAL: Food enhances the oral absorption and bioavailability of cinacalcet. According to the product labeling for cinacalcet, administration with a high-fat meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of cinacalcet by 82% and 68%, respectively, compared to administration in the fasting state. The Cmax and AUC were increased 65% and 50%, respectively, when cinacalcet was administered with a low-fat meal compared to fasting.

MANAGEMENT: To ensure maximal oral absorption, cinacalcet should be administered with or immediately after a meal. The tablets should be taken whole and not divided or crushed.