INTS: 1. Ethylene Deltenone (Cas No. 5371-36-8)
            2. Estra-4,9-diene-3,17-dione.
            3. 3-Ethyl-enedioxy-estra-5(10)9,11-diene-17-one.

Molecular Formula:C29H35NO2

Molecular Weight:429.65

Mifepristone (also known as RU 486) is used to cause an abortion during the early part of a pregnancy. It is used up to week 7 of pregnancy (up to 49 days after the first day of your last menstrual period). Mifepristone blocks a natural substance (progesterone) that is needed for your pregnancy to continue. It is usually used together with another medicine called misoprostol.Mifepristone must not be used if you have a rare abnormal pregnancy that is outside the womb (ectopic pregnancy). It will not cause an abortion in this case. It may cause an ectopic pregnancy to rupture, resulting in very serious bleeding.

Mifepristone blocks the hormone progesterone needed to maintain the pregnancy. Because this hormone is blocked, the uterine lining begins to shed, the cervix begins to soften and bleeding may occur. With the later addition of the second medication, misoprostol, the uterus contracts and the pregnancy is usually expelled within 6 to 8 hours.
Because the woman decides when to take the second medication within the time frame of 24 to 72 hours after the first medication, she has some control over when she experiences the miscarriage and its side effects. Some women choose the Abortion Pill because of the privacy it offers. Some women feel empowered by taking an active role in the process.

Side Effects
Most of the side effects when using this early abortion option are caused by the second medication, misoprostol. Side-effects may include heavy bleeding, headache, nausea, vomiting, diarrhea, and heavy cramping.

Dosage :
Treatment with Mifebort and Misobort for the termination of pregnancy requires three office visits by the patient. Mifebort may be administered only in a clinic, medical office, or hospital, by or under the supervision of a gynecologist, able to assess the gestational age of an embryo and to diagnose ectopic pregnancies. Gynecologist must also be able to provide surgical intervention in cases of incomplete abortion or severe bleeding, if necessary. Mifebort. Unless abortion has occurred and has been confirmed by clinical examination or ultrasonographic scan, the patient takes two 200 mg tablets (400 mg) of Misobort orally.

According to the current RCOG abortion evidence-based clinical guideline:[6]

• All methods of first-trimester abortion carry a small risk of failure to terminate the pregnancy, thus necessitating a further procedure. The risk for surgical abortion is around 0.23% and for medical abortion between 0.1% and 1.4% (depending on the regimen used and the experience of the centre).
• Medical abortion using mifepristone plus prostaglandin is the most effective method of abortion at gestations of less than 7 weeks.
• Conventional vacuum aspiration should be avoided at gestations below 7 weeks.
• Early vacuum aspiration using a rigorous protocol (which includes magnification of aspirated material and indications for serum βhCG follow-up) may be used at gestations below 7 weeks, although data suggest that the failure rate is higher than for medical abortion.

Mifepristone can also be used in smaller doses as an emergency contraceptive; if taken after sex but before ovulation, it can prevent ovulation and so prevent pregnancy. In this role, a 10 mg dose is not as effective as the 600 mg dose, but has fewer side-effects.[7] Mifeprex and Mifegyne are only available in 200 mg tablets.[8] A review of studies in humans found that the contraceptive effects of the 10 mg dose were probably due mainly to its effects on ovulation, and not inhibition of implantation, but "the knowledge of the mechanism of action remains incomplete." Treatment with 200 mg of mifepristone changes steroid receptor expression in the fallopian tube, inhibits endometrial development, and effectively prevents implantation.[9]