Bioequivalence of a darunavir/cobicistat fixed-dose combination tablet versus single agents and food effect in healthy volunteers.

Background: Darunavir requires pharmacokinetic enhancement to increase its bioavailability. Cobicistat is potentially an alternative pharmacokinetic booster to ritonavir. Bioequivalence of a darunavir/cobicistat fixed-dose combination (FDC) versus darunavir and cobicistat co-administered as single agents and the effect of a high-fat meal on the pharmacokinetics of the FDC were evaluated. Methods: In this Phase I, open-label, randomized, three-panel, crossover study (NCT01619527), healthy volunteers received a single dose of darunavir (800 mg) with cobicistat (150 mg) as either an FDC or as single agents co-administered under fasted (panel 1, n=74) or fed (breakfast, panel 2, n=40) conditions, or as the FDC under fasted versus fed (high-fat breakfast) conditions (panel 3, n=19), with a ≥7 day washout period between treatments. Pharmacokinetic profiles, safety and tolerability were assessed. Results: 90% confidence intervals of the least square mean ratios for darunavir and cobicistat maximum plasma concentration and area under the plasma concentration– time curve (AUC) were all within 80.00% and 125.00% in panels 1 and 2. Administration of the FDC with a highfat breakfast significantly increased darunavir maximum plasma concentration 2.27-fold and AUC 1.63–1.70-fold, whereas cobicistat pharmacokinetics were unaffected. No volunteers discontinued due to adverse events (AEs). All AEs were grade 1 or 2. Overall, 27 (20%) and 26 (20%) volunteers had ≥1 AE at least possibly related to darunavir and cobicistat, respectively. Conclusions: Bioequivalence of the darunavir/cobicistat 800/150-mg FDC was demonstrated versus darunavir and cobicistat co-administered as single agents under fasted or fed conditions. Food increased darunavir exposure, therefore, darunavir/cobicistat should be administered with food.