Efavirenz‐ but not nevirapine‐based antiretroviral therapy decreases exposure to the levonorgestrel released from a sub‐dermal contraceptive implant

Abstract

Over a 24-week period, LNG concentrations were 40-54% lower in women on EFV-based ART, despite their having a significantly lower body weight, compared to those not on ART. In women on NVP-based ART, LNG concentrations were 32-39% higher than those observed in the control group, a difference partially explained by body weight. These data confirm a significant drug interaction occurs between the LNG implant and EFV, adding to growing concern for reduced contraceptive efficacy with their combined use. In contrast, these data support use of the LNG implant with NVP-based ART.