Contraceptives: A Look at the Future

Abstract

Some future contraceptives promise new reliability and convenience. The Silastic vaginal ring is expected to be available worldwide in the mid-1990s. The ring releases 250 to 280 mcg of levonorgestrel and 180 mcg of estradiol, a combination that virtually eliminates ovulation. A low-dose ring is also being investigated. Contraceptive implants of Silastic polymer-based rods or capsules are inserted under the skin; these slowly release progestogen that suppresses ovulation. These implants are currently available in Scandinavian countries, Indonesia, and South America. The cervical cap has recently returned to the US market. The woman applies a spermicidal cream or jelly in the cap and places it over her cervix. It can be left in place for up to 36 hours. At present, 80 countries use various injectable drugs that inhibit ovulation for 2-3 months, but they are not yet approved in the USA because of their potential side effects. Under investigation in the US and elsewhere are antispermatogenic agents that create temporary infertility by interfering either with spermatogenesis or with the sperm's ability to fertilize ova. The agents can be given by injection or taken orally. Developed in France and undergoing clinical trials in the US, RU-486 is a pill that disrupts gestation by interfering with progesterone receptors in the inner lining of the uterus. RU-486 can be used to induce early nonsurgical abortions or routinely each month just before menstruation is due.