Sino-implant (II)® continuation and effect of concomitant tenofovir disoproxil fumarate-emtricitabine use on plasma levonorgestrel concentrations among women in Bondo, Kenya

Abstract

Objective: The objective was to assess associations between tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) exposure and levonorgestrel (LNG) concentrations among Kenyan HIV prevention trial participants using Sino-implant (II) LNG implants for contraception.

Methods: Women were offered implants among other contraceptive methods, were randomized to daily TDF-FTC or placebo, and followed monthly up to 56weeks. Associations between TDF-FTC exposure and mean LNG values were analyzed with linear mixed models.

Results: Of 739 women, 29 (3.9%) received implants with no incident pregnancies and one discontinuation. Mean LNG concentrations over 56weeks among 28 women contributing data ranged between 214.0 and 659.8pg/mL with no significant difference between TDF-FTC and placebo arms or between variable levels of TDF-FTC adherence.

Conclusion: Concomitant TDF-FTC use was not associated with a significant change in plasma LNG concentrations among women using Sino-implant (II) in the first year of use.

Trial registration: ClinicalTrials.gov NCT00625404.

Keywords: Levonorgestrel implant; Levonorgestrel levels; Long-acting reversible contraception; Preexposure prophylaxis; Prospective study; Sino-implant (II).