She noted that the findings have important implications for developers of vaginal rings designed to prevent HIV transmission as well as provide hormone-based contraception.
Dr. Scarsi and colleagues conducted a phase 2, international, nonrandomized, parallel pharmacokinetic study comparing levels of estrogen in the form of ethinyl estradiol (EE) and progestin in the form of etonogestrel among women with HIV infection who had not yet begun ART, as well as women on efavirenz- or atazanavir-based regimens.
Participants 16 years and older from centers in Africa, Asia, and North and South America were enrolled. The patients had to be willing to use a second, nonhormonal form of effective contraceptive, and if they were not on ART had to have CD4 cell counts of 350 cells/m3 or higher at screening. Participants on ART had to be on stable therapy for at least 30 days, and have HIV-1 RNA of 400 copies/mL or less.
A total of 25 control subjects, 25 women on efavirenz, and 24 on atazanavir were available for the primary pharmacokinetic analysis.