Mifepristone (RU 486)
• Synthetic steroid that prevents progesterone from
binding to progesterone and glucocorticoid receptors
• Mechanism(s) of action
– Disrupts follicular maturation and endocrine
function of the granulosa cell
– Disrupts midcycle LH surge
– Interrupts hormonal support of the endometrium,
making it asynchronous
LaValleur J.  Obstet Gynecol Clin North Am.  2000;27(4): 817-839.
Marions L, et al. Obstet Gynecol 2002;100:65-67.
Glasier A,  et al. N Engl J Med. 1992; 327(15):1041-1044.