Regression of uterine leiomyomata to the antiprogesterone RU486: dose-response effect.

OBJECTIVE

To study the response of uterine leiomyomata to three daily doses of RU486 (5, 25, and 50 mg).

DESIGN

Prospective nonrandomized trial of women with symptomatic leiomyomata.

SETTING

Patients from the clinical practice of the authors at the University of California, San Diego Medical Center.

PATIENTS

Ten patients with symptomatic leiomyomata previously reported after treatment with 50 mg of RU486 daily for 3 months. Eleven patients treated with 25 mg of RU486 daily and nine patients placed on 5 mg of RU486 daily for 12 weeks.

MAIN OUTCOME MEASURES

Changes in leiomyomata volume as measured with vaginal ultrasounds at baseline and monthly thereafter. Frequent blood samples for hematology, chemistry, and hormone levels were obtained. Twenty-four-hour urine collections for free cortisol and creatinine were obtained at baseline and at 12 weeks.

RESULTS

All three doses induce ovarian acyclicity. Administration of 50 mg of RU486 decreases leiomyomata volume to 78.1% +/- 4.8% of baseline at 4 weeks, 60.5% +/- 6.6% at 8 weeks, and 51.0% +/- 9.2% after 12 weeks of treatment. Regressive response in patients treated with 25 mg of RU486 daily was 76.3% +/- 5.0% of baseline at 4 weeks, 54.0% +/- 5.1% at 8 weeks, and 44.0% +/- 5.0% after 12 weeks. At 5 mg of RU486 leiomyomata volume was 80.6% +/- 8.3% of baseline after 4 weeks, 63.7% +/- 14.6% after 8 weeks, and 74.4% +/- 19.8% after 12 weeks of therapy.

CONCLUSIONS

Although acyclicity is seen at all three doses, an effective dose to cause a clinically significant (50%) decrease in leiomyomata volume appears to be 25 mg daily.