Steroid releasing vaginal rings
Nuttal, I.D.; Elstein, M.
Acta Europaea Fertilitatis 11(3): 225-230
1980
ISSN/ISBN: 0587-2421 PMID: 6781195 Document Number: 158418
In discussing steroid-releasing vaginal rings, the different types of progestogens used are outlined along with their various delivery systems and the history of the vaginal ring is summarized. A new derivative is levenorgestrel, and this steroid has a marked anti-estrogenic systemic action, with a more mild local genital tract effect. It is the action of this progestogen which has been most widely studied in conjunction with the vaginal rings along with the other 19 norsteroid, norethisterone. There are several methods of delivery of a slow release of progestogens, which have a prolonged contraceptive action. Some of them are in general use; others are still in the research stage. They are the following: injectable progestogens; progestogen releasing IUDs; silicone implants; intracervical devices; and contraceptive vaginal rings. The possibily of using the vagina as a route of administration of contraceptive steroids has several advantages. 1 advantage is that a reservoir placed in the vagina from which steroids could be released at a constant rate would avoid the inconvenience associated with the oral route of administration. The most effective progestogen would appear to be levonorgesterel, which has a potent anti-ovulatory action along with 1 of the lowest incidences of breakthrough bleeding. Clinical trials show that inhibition of ovulation plus local genital tract effects has been the goal of the steroid vaginal rings, and menstrual irregularity has been the price paid. A multi-center trial was formulated by the World Health Organization using levonorgestrel and norethisterone as the basic progestogens released in low dose from a vaginal delivery system. The findings of this trial and subsequent trials are reported.