Drug interactions between antiretrovirals and hormonal contraceptives

Significant advances in antiretroviral therapy have transformed HIV into a chronic manageable disease, and millions of women living with HIV now have the opportunity to reconsider their reproductive choices, be it contraception or pregnancy planning. Hormonal contraceptives are metabolized by cytochrome P450 isoenzymes and sulfate and glucuronide conjugation in the liver. Many antiretrovirals have inducing or inhibiting effects on the cytochrome P450 system. As such, the pharmacokinetics of hormonal contraceptives can be affected by antiretroviral therapy with potential for significant clinical impact.

This article presents the pharmacology and metabolism of selected antiretrovirals and hormonal contraceptives, and highlights the potential interactions between these two classes of drugs. Furthermore, the authors present the pharmacokinetic evidence of interactions from available clinical trials, product monographs, and international conference abstracts.

Drugs most likely to interact with combined oral contraceptives, transdermal and implant contraceptives include protease inhibitors, the NNRTIs efavirenz and nevirapine, and cobicistat-boosted elvitegravir. There do not appear to be significant pharmacokinetic interactions with depo-medroxyprogesterone or intrauterine systems and antiretrovirals, although further study is needed. Clinicians working with HIV-positive women need to know the significance of these interactions in order to properly counsel patients and prevent unplanned pregnancies.