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

Contraception. 2015 Mar;91(3):248-52. doi: 10.1016/j.contraception.2014.10.008. Epub 2014 Oct 22.


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: NCT00625404.

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

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenine / analogs & derivatives*
  • Adenine / pharmacology
  • Adolescent
  • Adult
  • Antiviral Agents / pharmacology*
  • Contraceptive Agents, Female / administration & dosage*
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacology
  • Drug Combinations
  • Drug Implants
  • Emtricitabine
  • Female
  • HIV Infections / prevention & control
  • Humans
  • Kenya
  • Levonorgestrel / administration & dosage*
  • Levonorgestrel / blood*
  • Longitudinal Studies
  • Organophosphonates / pharmacology*
  • Polypharmacy
  • Prospective Studies
  • Tenofovir
  • Young Adult


  • Antiviral Agents
  • Contraceptive Agents, Female
  • Drug Combinations
  • Drug Implants
  • Organophosphonates
  • Deoxycytidine
  • Levonorgestrel
  • Tenofovir
  • Emtricitabine
  • Adenine

Associated data