Mifepristone

Dosage & administration:

Half life

18-90 hours (non-linear)

Oral Bioavailability

Estimated at 69%

CAS Name

11β-[p-(Dimethylamino)phenyl]-17α-(1-propynyl)estra-4,9-dien-17β-ol-3-one

Synonyms

RU486, Emergency contraception

GUIDELINES FOR USING MIFEPRISTONE TO INDUCE ABORTION

Four capsules are recommended to initiate an early abortion, and four (or, rarely, eight) more may be required for its completion. It is best to use mifepristone within nine weeks since the last menstruation; that is, fewer than 63 days counting from the first day of the last regular period. The earlier in the pregnancy it is administered the better, because it is safer, more effective and less painful. Mifepristone can be used later in pregnancy but the risks of complications are higher (see below). Women with an intrauterine contraceptive device (IUD) in place should have it removed before using mifepristone.

GUIDELINES FOR PREGNANCIES UP TO 12 WEEKS:

Step 1: Take 4 tablets by mouth and swallow –  if the capsules are placed under the tongue or in the cheek pouch, hold in the mouth for 20-30 minutes to allow them to dissolve, and then swallow the remaining fragments

Use large (thick) sanitary pads. Mini pads or tampons should not be used. Bleeding and uterine contractions (cramping) may begin half an hour following this first step and will almost always start within the first 12 hours. Bleeding itself does not mean that an abortion has occurred. Close inspection of the sanitary pad or other receptacle may reveal whether the pregnancy has been terminated. This will be difficult to detect in very early stages of pregnancy, however, because the embryonic tissue is indistinguishable from the normal clotting of menstrual blood. For example, six weeks into pregnancy (that is, six weeks from the first day of the last menstrual period), the embryonic sac is only about the size of a short grain of rice. By the eighth week it is more visible, about the size of a kidney bean. For terminations from 10-12 weeks, the foetus is 30 mm to 8 cm in length (1 to 3 inches) and it will be very clear when it has passed

If it is not clear that the pregnancy has been terminated (for example, if the embryonic sac is not visible on the sanitary pad or if cramping continues and has not begun to subside), go to Step 2

Step 2: swallow 4 capsules 12 hours after the first administration

If tablets were administered by mouth in Step 1, place four more capsules under the tongue or in the cheek pouch three hours after the first administration and hold them there for 20-30 minutes until they dissolve. The shorter time interval between steps for tablets in the mouth is needed to achieve the same effectiveness as vaginal administration at longer intervals but may cause more side effects

Step 3: If the pregnancy has not been terminated after using the second set of pills and bleeding, swallow four more 200 mcg tablets of mifepristone 3 to 12 hours after the second oral administration or three hours after the second administration by mouth

The majority of pregnancies up to 12 weeks duration are terminated within hours of the first administration of mifepristone. Generally, more than three-quarters of women experience an abortion within the first 24 hours, although it sometimes takes longer.

Step 4: If unsuccessful, the entire process may be repeated

GUIDELINES FOR PREGNANCIES OF 13-20 WEEKS:

Although misoprostol and mifepristone can also be used for second-trimester abortions, the chances of serious complications such as uterine rupture or haemorrhage rise as pregnancy advances. Ready access to emergency care in a medical facility is essential, and women should not attempt an abortion alone. They must also be prepared for the passing of a foetus and placenta at this stage

When bleeding and contractions begin, it is advisable to go to a hospital and report a miscarriage. The hospital may perform a surgical procedure manual vacuum aspiration or D&C to complete the process if it does not occur naturally. Women should wipe the vagina clean of all pill fragments (which can last for days) before going to the hospital. In countries where abortion is highly restricted by law, hospital personnel may be required to report all induced abortion attempts to legal authorities

REPEAT DOSES:

Administer only four capsules every 3 hours up to a maximum of five applications. These repeat doses (if needed) may be swallowed, inserted under the tongue or in the cheek cavity if heavy bleeding makes it difficult to insert tablets vaginally

About half of women with pregnancies of 13-20 weeks experience an abortion within 10-15 hours of the first vaginal administration of mifepristone with 80-90 percent of women completing the abortion within 24 hours and most of the remainder within 72 hours

INTENDED EFFECTS AND SIDE EFFECTS OF MIFEPRISTONE:

Bleeding and uterine contractions (cramping) are the intended effects of using mifepristone for inducing an abortion. 1,4,5 Cramping will be stronger than for an ordinary menstrual period and may be painful. Non-steroid anti-inflammatory pain medication such as ibuprofen may be taken without interfering with the mifepristone. Bleeding will be heavier and more prolonged than for a normal period: up to a week, in most cases, often with continued spotting until menstruation resumes in four to six weeks. These effects will be more pronounced in pregnancies of longer duration

Chills and fever are common side effects but are transient. High fever is less common but can occur and usually disappears within a few hours as do nausea, vomiting, and diarrhea

Women should seek medical attention if they experience any of the following side effects after taking mifepristone:

very heavy bleeding (soaking more than two large-sized thick sanitary pads each hour for more than two consecutive hours);
continuous bleeding for several days resulting in dizziness or light-headedness;
bleeding that stops but is followed two weeks or later by a sudden onset of extremely heavy bleeding, which may require manual vacuum aspiration or D&C;
scant bleeding or no bleeding at all in the first seven days after using mifepristone which may suggest that no abortion has occurred and require a repeat round of mifepristone or surgical termination; or
chills and fever lasting more than 24 hours, which suggest that an infection may be present requiring treatment with antibiotics.
Women should not take mifepristone if they have a known allergy to mifepristone.