Quad reduces levels of oral contraceptives
This open-label fixed-sequence study investigated the pharmacokinetics of a combined oral contraceptive containing 25 ug ethinylestradiol and norgestimate with a fixed dose combination tablet containing elvitegravir, cobicistat, FTC and TDF (Quad).
Steady-concentrations of ethinylestradiol, norelgestromin (the active metabolite of norgestimate), EVG and cobicistat were determined in 15 HIV-negative women receiving the oral contraceptive alone or with the quad tablet. Coadministration decreased the AUC of ethinylestradiol by ~25% and increased the AUC of norelgestromin by ~2-fold. Concentrations of elvitegravir and cobicistat were within the range of values observed in previous studies. Changes in progesterone and FSH were similar in both treatment phases, but changes in LH were greater in the combination phase.
In light of the decrease in ethinylestradiol, it is recommended that when coadministered with the Quad tablet, oral contraceptives should contain at least 30 µg ethinylestradiol.
German P et al. EVG/cobicistat/FTC/TDF and oral contraceptives pharmacokinetic interaction between norgestimate/ethinyl estradiol and EVG/COBI/FTC/TDF single tablet regimen. 12th International Workshop on Clinical Pharmacology of HIV Therapy, 13-15 April 2011, Miami. Oral abstract: O_17.