Pharmacodynamics of a contraceptive vaginal ring releasing 3-keto-Desogestrel

Abstract

The pharmacodynamic effects of a new type of 3-keto-Desogestrel [3kDOG] releasing vaginal ring was studied in a group of 20 normally ovulating women during a period of 21 days continuous use. Peripheral blood samples were taken for the estimation of progesterone and oestradiol levels, ultrasound tracking for follicular growth and cervical mucus sampling for scoring [modified Insler] and sperm penetration testing during a control, treatment and recovery period. Additional blood samples were taken for the estimation of 3kDOG levels during the treatment period. After a control cycle, twenty normally ovulating women were selected and randomly divided into two groups. Group A were given a vaginal ring on day 5 of the menstrual cycle releasing 30 ug/24 hours of 3kDOG and group B a similar ring releasing 15 ug/24 hours of kDOG.Of the treatment cycles, none showed an ovulatory pattern in group A and there was only one in group B, the respective mean plasma levels of 3kDOG were 0.38 and 0.25 pmol/ml. The formation of “cysts” or persistent follicles was common to both groups, 6 out of 10 subjects in group A and 8 out of 10 subjects in group B had “cysts” greater than 25mm in diameter in the treatment cycle, this had become 5 out of 10 and 8 out of 10, respectively, in the recovery cycle. A comparison of the cervical mucus scores and sperm penetration of cervical mucus showed a significant reduction between the control and treatment groups but no significant difference between the two groups. The bleeding profiles showed an increase in percentage of bleeding days in both treatment groups to 25% in group A and 21.7% in group B [cf, 17.1%, 15.9%, respectivly, in control month]; there being no statistical difference between groups.In conclusion, it is believed that given the efficacy demonstrated and the low level of menstrual disturbances found, this system warrants further investigation as a means of contraception as it appears to offer a better compromise than previous vaginal ring systems.