Antiprogestins for contraception?

Antiprogestins could be a very promising group of compounds for contraception because they counteract the effects of progesterone, a key hormone for normal reproductive functioning. Great efforts have therefore been devoted to testing various ways of using these compounds for family planning. Most of this work has involved mifepristone; other antiprogestins have not been available for trials. With a few exceptions, the outcome of the studies performed to date has not met expectations. The most promising approaches seem to be the use of antiprogestins for emergency contraception, perhaps also as a daily pill when the dose is high enough to block ovulation, and in sequential regimens followed by a progestin. Given that antiprogestins differ in their affinity for target organs, better results could possibly be achieved by using more specific compounds than mifepristone. It is hoped that a wider choice of antiprogestational compounds will soon become available for research.