Abstract

PIP: Most of this review of the development of steroid-containing vaginal rings for contraception consists of a table listing drug dose, effect of the ring on bleeding and ovulation, and citation. The advantage of formulating a medicated vaginal ring is that the first-pass effect of an oral route of administration is avoided. Blood levels of the steroid are constant throughout the day. Low-dose progestin rings generally result in menstrual bleeding anomalies. Bleeding patterns improve when the progestin dose is raised and estradiol is added. A levonorgestrel ring developed by WHO has been fairly acceptable, with normal bleeding patterns in 50% of users, 365 ovulatory cycles, and pregnancy rates of 9.8% in women weighing 80 kg, and 1.7% in women 40 kg. Another approach is to combine progestin and estrogen. A ring releasing 120 or 150 mcg 3 keto-desogestrel and 15 mcg ethinyl estradiol daily has prevented ovulation and left bleeding patterns intact. The rings are used for 21 days, and removed for 7, and last 3 months. Generally about 70% of women find vaginal rings acceptable.