The Antiprogestogen Mifepristone: A Review

Mifepristone is a potent antiprogestogen with antiglucocorticoid activity. It acts at the level of the progesterone receptor and is a competitive progesterone antagonist.Most clinical studies have focussed on the use of mifepristone for early medical abortion. The manufacturers recommended regimen for early medical abortion comprises of 600mg of mifepristone in combination with the prostaglandin gemeprost. However, mifepristone 200mg in combination with the synthetic prostaglandin analogue misoprotol or gemeprost has been shown to be a cost effective regimen for early medical abortion. Mifepristone in combination with a prostaglandin has also been shown to be effective for second trimester medical abortion reducing the induction abortion interval. More recently mifepristone has been shown to be effective for termination of pregnancy at 10-13 weeks amenorrhoea, at which gestations surgical methods are almost exclusively used. Mifepristone administered 48 hours prior to surgical vacuum aspiration is effective for cervical priming.Mifepristone alone or in combination with a prostaglandin can be used for induction of labour following intrauterine death and medical management of early fetal demise (missed abortion and anembrynic pregnancy).Mifepristone has been shown to be an effective emergency contraceptive up to 120 hours after unprotected intercourse with high patient acceptability. It may have other potential uses, which include its use in metastatic breast cancer, Cushing's syndrome and shrinking of uterine leiomyomata. It may prove to be an effective “once a month pill”.In conclusion mifepristone in combination with a prostaglandin is effective for medical abortion at all gestations. Mifepristone can be used in the medical management of miscarriage and for induction of labour and is a potent postcoital contraceptive and an effective cervical priming agent. Since mifepristone was first used for medical abortion there has been a stigma associated with investigating the other potential uses of this drug.