A Pharmacokinetic Evaluation of Levonorgestrel Implant and Antiretroviral Therapy

The use of hormone contraception poses a significant challenge for the estimated 16 million HIV-infected women of childbearing age. This is due to known drug interactions with antiretroviral therapy (medicines used to treat HIV) that may jeopardize contraception effectiveness. By evaluating the impact of antiretroviral therapy on a levonorgestrel subdermal implant, the most widely available hormone implant in low and middle-income countries, this study will translate its findings into an evidence-based approach to co-manage these important medications. The investigators hypothesize that women receiving nevirapine or efavirenz-based antiretroviral therapy will have a significant decrease in the mean levonorgestrel plasma concentration measured six months after the implant's insertion as compared to those women who are not taking antiretroviral therapy. Although the implant's efficacy may be retained initially, the investigators propose that a decrease in levonorgestrel concentrations in women receiving antiretroviral therapy may jeopardize the implant's effectiveness near the end of its intended duration of use (5 years).