The antiprogestational agent RU 486 as an abortifacient in early human pregnancy: a comparison of three dose regimens.

Three different regimens of RU 486, a progesterone receptor blocking agent, were compared for their ability to terminate early human pregnancy. One-hundred-fifty-three healthy women with a gestational length less than 49 days from the last menstrual period were recruited to the study and randomly allocated to one of three treatment regimens: 1) RU 486 10 mg x 2 for seven days; 2) RU 486 25 mg x 2 for seven days; or 3) RU 486 50 mg x 2 for seven days. No significant difference in efficacy was seen between the three dose regimens. Treatment with 10 mg x 2 x VII resulted in 73 per cent complete abortions, 25 mg x 2 x VII in 66 per cent and 50 mg x 2 x VII in 64 per cent complete abortions. Response to treatment, measured as reported onset of bleeding and passage of products of conception, however, occurred significantly later on the 10 mg x 2 regimen than on the other two dose regimens. In each treatment group, women who subsequently aborted completely had significantly lower pretreatment levels of hCG than women with incomplete abortion or continuing pregnancy. The treatment was well tolerated by the women and except for one woman who experienced a profound bleeding necessitating a blood transfusion, no serious side effects were seen.