CLINICAL EFFICACY OF THE ANTIPROGESTERONE RU486 IN THE TREATMENT OF ENDOMETRIOSIS AND UTERINE FIBROIDS

To evaluate the long-term effects of treatment with RU486 and to test its efficacy in endometriosis, a 3-month trial was conducted to evalua te the effects of daily administration (100 mg/day or similar to 2 mg/ kg/day) on the functional activity of the reproductive axis, as well a s implants, in patients with symptomatic pelvic endometriosis. All wom en became amenorrhoeic and acyclic. However, ovarian suppression was i ncomplete. In 24 h sampling studies, mean luteinizing hormone (LH) and LH pulse amplitude were increased without a change in LH pulse freque ncy. Additionally, an antiglucocorticoid effect was demonstrated. Trea tment resulted in improvement in pelvic pain in all subjects without s ignificant changes in the extent of disease as evaluated by laparoscop y. We also attempted to reduce the growth of uterine fibroids by using 50 mg/day of RU486 for 3 months in 10 patients. Myoma size decreased similar to 22% at 4 weeks, 39% at 8 weeks and 49% at 12 weeks. Serum c oncentrations of LH, androstenedione and testosterone increased in the first 3 weeks of treatment and then returned to baseline. In conclusi on, daily administration of RU486 resulted in ovarian inhibition and m enstrual acyclicity and in an improvement in the pain associated with pelvic endometriosis and decreased the size of uterine fibroids. This ovarian inhibition was achieved without oestrogen deprivation and may provide a novel long-term approach to the treatment of ovarian steroid -dependent disease processes.