Effects of tampon co-usage on the pharmacokinetics of segesterone acetate and ethinyl estradiol released from Annovera Vaginal Ring System

Document Type

Article (peer-reviewed)

Publication Date

10-17-2025

Abstract

Objective: To evaluate the effects of tampon co-usage on the pharmacokinetics (PK) of segesterone acetate (SA) and ethinyl estradiol (EE) released from Annovera Contraceptive Vaginal Ring System (CVS) with a 21-day in/7-day out regimen. Study Design: We enrolled 24 participants in an open-label crossover study in Canada and the United States. Participants used combined oral contraceptive pills for 28 days before randomization (1:1) to either Annovera and tampon co-usage (using four tampons daily on days 2-5 keeping Annovera in place) or Annovera alone for one 28-day cycle; in the next cycle participants switched treatments. We evaluated the steady-state interval for SA and EE from day 2-5 for concomitant Annovera and tampon use. We measured serum SA and EE at each timepoint using fully validated LCMS/MS methods. The primary PK endpoint was AUC of SA and EE on cycle days 2 to 3 (AUC(2-3)). Bioequivalence is established if the 90% CI of the geometric mean ratio (GMR) for AUC(2-3) is wholly contained within (0.80-1.25). Results: We observed bioequivalence for both SA and EE with GMRs of 0.98 (90% CI: 0.921, 1.043) and 0.97 (90% CI: 0.91, 1.026), respectively for AUC(2-3), and also for AUC from day 2 to day 5 for both SA and EE with GMRs of 1.02 (90% CI: 0.99, 1.06) and 1.02 (90% CI: 0.97, 1.087), respectively. We observed no significant safety issues or serious adverse events. Conclusions: Individuals using Annovera with four consecutive days of tampon use did not experience a change to SA or EE absorption. Thus, light/regular tampon co-usage for up to four consecutive days should not impact contraceptive efficacy or bleeding profile. Implications statement: A significant proportion of reproductive-age women use tampons when experiencing vaginal bleeding; they can be reassured that tampon and contraceptive ring co-usage should not affect contraceptive efficacy of the segesterone acetate/ethinyl estradiol contraceptive vaginal ring.

DOI

10.1016/j.contraception.2025.111274

Language

English

https://doi.org/10.1016/j.contraception.2025.111274

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