Drug Interaction Report

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the systemic exposure to vilanterol following oral inhalation, as it is primarily metabolized by the isoenzyme. The interaction has been studied with fluticasone-vilanterol and ketoconazole. When fluticasone-vilanterol (200 mcg-25 mcg once daily for 7 days) was coadministered with ketoconazole (400 once daily for 11 days) in healthy subjects, fluticasone and vilanterol systemic exposure (AUC) were 36% and 65% higher, respectively, compared to coadministration with placebo. The increase in fluticasone exposure was associated with a 27% reduction in 24-hour weighted mean serum cortisol, whereas the increase in vilanterol exposure was not associated with an increase in beta-2 adrenergic systemic effects on heart rate or blood potassium.

MANAGEMENT: Due to the risk of cardiovascular adverse effects such as increases in pulse rate and blood pressure and ECG changes such as flattening of the T wave, prolongation of the QTc interval, and ST segment depression, caution is recommended when medications containing vilanterol are coadministered with potent CYP450 3A4 inhibitors such as itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, nefazodone, cobicistat, delavirdine, protease inhibitors, and ketolide and certain macrolide antibiotics. An increased risk of systemic corticosteroid effects should also be considered when fluticasone-vilanterol is used.

ADJUST DOSING INTERVAL: Food significantly enhances the oral bioavailability of telaprevir. When given with a meal containing 533 kcal and 21 g fat, telaprevir systemic exposure (AUC) increased by 237% compared to administration under fasting conditions. The type of meal also affects the exposure to telaprevir. Relative to fasting, telaprevir AUC increased by approximately 117% with a low-fat meal (249 kcal; 3.6 g fat) and 330% with a high-fat meal (928 kcal; 56 g fat). In Phase 3 clinical trials, telaprevir doses were administered within 30 minutes of completing a meal or snack containing approximately 20 grams of fat.

MANAGEMENT: Telaprevir should be administered with food containing approximately 20 grams of fat. Patients should be advised that the fat content of the meal or snack is critical to the absorption of telaprevir. Food taken with telaprevir should be ingested within 30 minutes prior to each dose. Examples of some foods that could be taken with telaprevir include: bagel with cream cheese; half cup of nuts; 3 tablespoons of peanut butter; 1 cup of ice cream; 2 ounces of American or cheddar cheese; 2 ounces of potato chips; or half cup of trail mix.