Effect of the antiprogestin onapristone on follicular growth in women

Horacio B. Croxatto, Ana M. Salvatierra, Blanca Fuentealba, Christian Zurth, Sybille Beier

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


The effects of the antiprogestion onapristone on the menstrual cycle were assessed in surgically sterilized volunteer women. The steroid was given orally at the dose of 5, 15 or 50 mg/day, from day 5 to day 11 of the cycle. Ovarian ultrasonography and hormonal determinations in plasma and urine were used to monitor the pre-treatment, treated and post-treatment cycles. Onapristone, given at a dose of 5 mg/day, arrested follicular growth and inconsistently. The dose of 15 or 50 mg/day arrested follicular growth and oestradiol increase and delayed gonadotrophin surge, extending the length of the follicular phase in five of seven women in each group. After discontinuation of treatment the leading follicle resumed its growth and ovulation occurred as judged by the elevation of plasma progesterone, preceded in most but not all cases by an echographic image of follicular collapse. The ensuing luteal phases were not significantly altered in length or plasma progesterone concentration. Cortisol concentrations were unaffected and no serious side-effects were recorded. The antifolliculotrophic effect of onapristone demonstrated here, together with previous reports of similar activity of mifepristone in women, indicate that this may be a general property of compounds that interfere with progesterone receptor function.

Original languageEnglish
Pages (from-to)1442-1447
Number of pages6
JournalHuman Reproduction
Issue number8
Publication statusPublished - Aug 1994


  • Antiprogestin
  • Follicular maturation
  • Human
  • Onapristone
  • RU486

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynaecology


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