Definition of mifepristone in English:


Pronunciation /ˌmifəˈpristōn/ /ˌmɪfəˈprɪstoʊn/


  • A synthetic steroid that inhibits the action of progesterone, given orally in early pregnancy to induce abortion.

    Also called RU-486 (a trademark)

    ‘The present study was planned to find a safe, simple and optimally effective regimen of mifepristone and misoprostol for abortion of pregnancy up to 63 days.’
    • ‘No studies have specifically compared mifepristone with levonorgestrel.’
    • ‘This medication has been shown to be effective for elective abortions and medical termination of pregnancy during the first trimester, leading to studies of the effect of mifepristone in term pregnancies.’
    • ‘On the first visit, after appropriate counseling and dating ultrasonography, the patient takes 600 mg of mifepristone orally.’
    • ‘Headache is the symptom most commonly reported either with estrogen plus progestin treatment or with mifepristone alone.’


1980s probably from Dutch mifepriston, from mife- (representing aminophenol) + -pr- (representing propyl) + -ist- (representing estradiol) + -one.