The most important example is mifepristone which is used to induce abortion (in the first trimester). Mifepristone is indi-cated for the medical termination of intrauterine pregnancy for pregnancies up to 49 days in duration. It has also been used successfully as an emergency contraceptive agent, in the treatment of inoperable meningiomas, as a cervical ripening and labour induction agent, and has significantly decreased the tumour volume in patients with uterine leiomyomas. Mifepristone is a substituted 19-nor steroid compound, derived from norethisterone, with potent anti-progestogenic activity, anti-glucocorticoid activity, and weak anti-androgenic activity.
Adverse effects include nausea, anorexia, abdominal pain, fatigue, and menorrhagia. Severe uterine bleeding, necessi-tating blood transfusions and curettage in some instances, may occur following therapeutic administration of mifepristone as sole therapy or in combination therapy with prostaglandin or misoprostol administration. Other adverse effects of mifepris-tone include dizziness, skin rashes, and elevated liver enzyme levels.
Due to mifepristone’s antiglucocorticoid activity, it is specu-lated that mifepristone overdose ingestions may result in adrenal failure, though this has not yet occurred. In case of mifepristone intoxication, treatment is symptomatic and supportive. In cases of severe uterine bleeding after elective abortion, curettage and transfusion of packed red blood cells may be necessary.