Ovulation inhibition with a new vaginal ring containing trimegestone

Area of Science:

• Reproductive endocrinology
• Pharmacology
• Contraception

Background:

• Hormonal contraception is a key area of reproductive health research.
• Developing novel delivery systems for progestogens is crucial for improving contraceptive efficacy and user experience.
• Trimegestone (TMG) is a progestogen with potential contraceptive applications.

Purpose of the Study:

• To determine the minimum daily release rate of trimegestone (TMG) from a vaginal ring required to effectively suppress ovulation in healthy women.
• To evaluate the dose-response relationship of TMG vaginal ring on ovulation inhibition and hormonal profiles.

Main Methods:

• A single-center, open-label, adaptive design clinical trial was conducted with 80 healthy female volunteers.
• Participants were assigned to vaginal rings releasing 46, 94, 147, or 184 µg/day of TMG for 28 days.
• Ovulation, follicular growth, endometrial thickness, and hormone levels (FSH, LH, estradiol, progesterone) were monitored throughout the study and follow-up period.

Main Results:

• Ovulation occurred in one subject at the lowest dose (46 µg/day), with no ovulations observed in higher dose groups (94, 147, 184 µg/day).
• Ovarian suppression and estradiol level reduction demonstrated a dose-dependent increase.
• Trimegestone (TMG) plasma levels were dose-proportional and declined over the treatment period; the treatment was safe and well-tolerated.

Conclusions:

• A daily release rate of 94 µg/day of trimegestone (TMG) from a vaginal ring is the lowest effective dose for inhibiting ovulation.
• The TMG-vaginal ring is a promising progestogen-only contraceptive candidate, offering a convenient once-a-month insertion method.