ABSTRACT
Contraceptive vaginal rings (CVRs) contain sex steroids that diffuse through a plastic
polymer ring at a constant rate and are absorbed directly through the vaginal epithelium
into the systemic circulation. This delivery system provides many advantages over
oral contraceptives (OCs), including avoidance of the first-pass effect through the
liver, constant serum steroid levels, longer duration of use, and greater bioavailability
of the hormones. CVRs containing progestin only are designed for continuous use for
3 to 6 months. Those containing progesterone alone are indicated for use in women
who are breastfeeding. Large clinical trials of progestin-containing CVRs demonstrated
good efficacy and safety of the CVR, with continuation rates similar to that of OCs.
CVRs containing a combination of estrogen and progestin are designed to be used for
1 to 12 months in a cyclic manner similar to OCs, with withdrawal bleeding in the
fourth week of each cycle. In clinical trials these CVRs have typical use efficacies
similar to OCs, with an acceptable pattern of bleeding.
KEYWORD
Contraception - sex steroid hormones - vaginal ring