The authors stated that co-administration of emtricitabine/tenofovir alafenamide and atazanavir/cobicistat led to expected increases in TAF and TFV exposures. This is consistent with the effect of a P-gP inhibitor on TAF. The increase in TAF and TFV exposures did not appear to pose safety concerns.
Emtricitabine/tenofovir alafenamide vs atazanavir/cobicistat
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Study Design
Twenty healthy subjects were enrolled in the open label, fixed sequence, 3-period cross over trial. Subjects received the following treatments: emtricitabine (FTC)/tenofovir alafanamide (TAF) 200 mg / 10 mg once daily with food on days 1 through 7; atazanavir boosted with cobicistat (ATV/COBI) 300 mg / 150 mg + FTC/TAF on days 8-14; and ATV/COBI on days 15-21. Pharmacokinetic assessments were performed on days 7, 14, and 21. Statistical comparisons for FTC, TAF, TFV (tenofovir), ATV and COBI were made using Geometric Least Square Means Ratios and associated 90% Confidence Interval no effect boundary of 70-143%. Safety was assessed throughout the study.
Study Results
Compared to administration of FTC/TAF alone, coadministration with ATV/COBI led to increases in TAF exposure (AUC) of 75% and Cmax of 80%; increases in TFV AUC of 248% and Cmax of 216% and Ctau of 273%. Coadministration did not affect pharmacokinetics of FTC, ATV or COBI. All treatments were well tolerated.
References
Custodio JM, Ting LS, S West, M Rhee, J Ling, J Weston, Kearny BP. Pharmacokinetic interaction between emtricitabine/tenofovir alafenamide and boosted atazanavir. 17th International Workshop On Clinical Pharmacology Of Hiv And Hepatitis Therapy. Washington, DC, USA. ; 2016.
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