Changes in sexual mores have led to the need for an effective emergency postcoital contraceptive agent. To meet this need various individual steroids, either alone or in combination, have been evaluated and shown to be effective in preventing pregnancy as a result of a single, unprotected coital act. No drug has received specific marketing approval in North America for this purpose. However, in western Europe, the combination of ethinyloestradiol and levonorgestrel is marketed specifically for use as a postcoital contraceptive agent. Intrauterine copper contraceptive devices have also been shown to be effective postcoital contraceptive agents, but their applicability is confined to a specific segment of the population. Other agents are also being investigated for their postcoital contraceptive effectiveness, including prostaglandins, anti-progestins, GnRH agonists, super agonists and antagonists, and HCG antagonists. Sufficient interest exists in postcoital contraception that the World Health Organization has undertaken, through their task force dealing with postcoital, once-a-month and menses-inducing agents, to develop other postcoital drugs.
