RU 4 86 or mifepristone
This drug blocks the action of progesterone, a naturally occurring hormone which sustains the nutritive uterine lining. As this lining withers, the embryo starves to death. Administration of mifepristone is followed 36-48 hours later by misoprostol, a synthetic prostaglandin, which causes uterine contractions that expel the unborn child. Some women will deliver while still at the clinic, while others will do so later, at home or at work. Bleeding can be quite heavy and lasts for an average of nine days. This method of abortion fails 5-10% of the time, and must then be followed by a surgical abortion.