Efficacy of the antiprogestin mifepristone (RU 486) prior to prostaglandin termination of pregnancy.

Forty-nine patients undergoing mid-trimester extra-amniotic prostaglandin termination of pregnancy were studied. Twenty patients acted as controls and received the standard hospital regime. Twenty-nine patients received the same regime, but in addition were given a single 200-mg oral dose of the antiprogesterone, mifepristone (RU 486), 24 h prior to prostaglandin infusion. The dose of prostaglandin required and the induction to abortion interval in the mifepristone-pretreatment group was significantly reduced. Complication rates were similar in both groups. Mifepristone is a safe and useful adjuvant therapy in mid-trimester prostaglandin termination.