Objective: This study sought to measure residual contraceptive hormone levels in vaginal rings as an adherence marker for monitoring product use in clinical trials.
Study design: Residual etonogestrel and ethinyl estradiol levels from used NuvaRings® of 26 self-reported adherent women enrolled in a clinical trial of vaginal ring acceptability were compared to those from 16 women who used NuvaRing® as their contraceptive choice.
Results: Twenty-one (81%) clinical trial rings had contraceptive hormone levels within the range of those used as a contraceptive choice. Five returned rings had unused or discordant levels of residual contraceptive hormones.
Conclusion: Residual vaginal ring drug levels could help assess adherence in clinical trials.
Keywords: Adherence; Contraception; HIV; Multipurpose technology; Vaginal ring.
Published by Elsevier Inc.