The investigators research team recently demonstrated that combined use of efavirenz (EFV) based antiretroviral therapy (ART), the only preferred first-line ART regimen in low and middle income countries, with a levonorgestrel (LNG)-releasing implant for one year reduced LNG plasma concentrations by approximately 50% compared to women not on ART. Importantly, the investigators also observed three unintended pregnancies (15%) in the investigators study group of women on EFV-based ART plus the LNG implant, in contrast to the <1% expected failure rate of the implant for women without drug interactions.~This study will determine if increasing the dose of the LNG-releasing subdermal implant effectively overcomes the known pharmacokinetic interaction with EFV- based ART. LNG pharmacokinetic results from the participants enrolled in this dose escalation study (n=28) will be compared to HIV-infected Ugandan women on standard dose LNG without concomitant EFV-based ART.
The purpose of this study is to determine whether increasing the dose of the levonorgestrel subdermal contraceptive implant will overcome a detrimental drug-drug interaction with efavirenz based antiretroviral therapy.