The Lancet HIV, September 2019
Effective family planning, which often involves the use of hormonal contraception, is an important component of care for women living with HIV. Unfortunately, some hormones have drug interactions with some antiretrovirals that may jeopardize hormone effectiveness or tolerability. Non-orally administered hormones may reduce the risk of these drug-drug interactions. The A5316 team sought to determine whether estrogen and progestin administered by a vaginal ring would be affected by oral ART containing either efavirenz or atazanavir/ritonavir. The results showed that hormone concentrations were significantly changed by both types of ART. The importance of understanding the pharmacology of vaginally administered drugs has particular relevance as vaginal rings are being developed for multipurpose prevention of both HIV and pregnancy.
https://www.thelancet.com/journals/lanhiv/article/PIIS2352-3018(19)30155-9/fulltext