Effects of mifepristone in vivo on decidual prostaglandin synthesis and metabolism.

ABSTRACT

PIP: Mifepristone is an effective abortifacient in combination with an exogenous prostaglandin (PG) but its mechanism is unknown. Mifepristone stimulates PG production from decidua in tissue culture. To determine whether this effect also operates in vivo, the authors treated 24 women with mifepristone 24, 36, an 48 hours prior to surgical termination. Decidua was removed at the time of operation and the ability of the tissue to generate PG in culture was subsequently assessed. Pretreatment with mifepristone 36 hours prior to termination of pregnancy resulted in an increased production of PGF2alpha in tissue culture (p0.01). A significant decrease in PGFM production was seen 24 hours after pretreatment with mifepristone in vivo (p0.01). These results suggest that the increased uterine activity observed after mifepristone administration may be due to stimulation of endogenous PG production and inhibition of PG metabolism.