Cervical softening with mifepristone (RU 486) after pretreatment with naproxen. A double-blind randomized study

Pretreatment with the progesterone antagonist mifepristone reduces the stiffness and facilitates mechanical dilatation of the uterine cervix. We studied the influence of the cyclo-oxygenase inhibitor naproxen on the softening effect of mifepristone on the cervix in thirty nulliparae. The patients were randomly allocated to receive 500 mg naproxen (group A) or placebo (group B) orally 60, 48, 36, 24 and 12 hours prior to vacuum aspiration. All patients received 100 mg mifepristone 48 and 36 hours before surgery. We found that the cervical softening effect of mifepristone was not antagonized by naproxen. The study indicates that the effect of mifepristone on the early pregnant cervix is not mediated through an increased production of prostaglandins.