Emergency pregnancy Termination and Emergency contraception
Mifepristone emergency pregnancy termination
mifepristone mechanism of action
Mifepristone is a 19-norsteroid with potent anti progestational and significant antiglucocorticoid,antiandrogenic activity.Given during the follicular phase, its antiprogestin action results in attenuation of the midcycle Gn surge from pituitary → slowing of follicular development and delay/failure of ovulation. If given during the luteal phase, it prevents secretory changes by blocking progesterone action on the
endometrium. Later in the cycle, it blocks progesterone support to the endometrium,
unrestrains PG release from it—this stimulates uterine contractions. Mifepristone also sensitizes the myometrium to PGs and induces menstruation.
If implantation has occurred, it blocks decidualization, so that conceptus is dislodged, HCG production falls, secondary luteolysis occurs–endogenous progesterone secretion decreases and cervix is softened. All these effects lead
to abortion.
Mifepristone is a partial agonist and competitive antagonist at both A and B forms of PR. In the absence of progesterone (during anovulatory cycles or after menopause) it exerts weak progestational activity—induces predecidual changes. Therefore, it is now regarded as ‘progesterone receptor modulator’ rather than ‘pure antagonist.’ The weak agonistic action is not manifest in the presence of progesterone.
The antiglucocorticoid action of usual doses is also not manifest in normal individuals because blockade of the negative feedback at hypothalamicpituitary
level elicits ACTH release → plasma cortisol rises and overcomes the direct antiglucocorticoid action. Amelioration of Cushing’s symptoms has been obtained with large doses.
Pharmacokinetics of mifepristone for pregnancy Termination
How long does it take for mifepristone to work?
Mifepristone is active orally, but bioavailability is only 25%. It is largely metabolized in liver by CYP 3A4 and excreted in bile; some enterohepatic circulation occurs; t½
20–36 hr.
Interaction with CYP 3A4 inhibitors (erythromycin,
ketoconazole) and inducers (rifampin,
anticonvulsants) has been reported
What is mifepristone used to treat? Mifepristone uses-
1. Termination of pregnancy of up to 7 weeks: 600 mg as single oral dose causes complete abortion in 60–85% cases. To improve the success rate, current recommendation is to follow it up 48 hours later by a single 400 mg oral dose of
misoprostol. This achieves >90% success rate and is the accepted nonsurgical method of early first trimester abortion. In place of oral misoprostol, a 1 mg gemeprost pessary can be inserted intravaginally. Mifepristone administered within 10 days of a missed period results in an apparent late heavy period (with dislodged blastocyst) in upto 90% cases. This procedure is generally safe, but prolonged
bleeding and failed abortion are the problems in some cases. Anorexia, nausea, tiredness, abdominal discomfort, uterine cramps, loose motions are the other side effects.(how to use mifepristone and misoprostol tablets)
2. Cervical ripening 24–30 hours before attempting surgical abortion or induction of labour, mifepristone 600 mg results in softening of cervix; the procedure is facilitated.
3. Postcoital contraceptive Mifepristone 600 mg given within 72 hr of intercourse interferes with implantation and is a highly effective method of emergency contraception. The subsequent menstrual cycle, however, is disturbed.
4. Once-a-month contraceptive A single 200 mg dose of mifepristone given 2 days after midcycle each month prevents conception on most occasions. Administering
mifepristone in late luteal phase to dislodge the embryo (if present) and to ensure menstruation irrespective of conception, has also been tried. These alternative methods of contraception, though attractive, may prolong/disrupt the next
menstrual cycle, and thus cannot be used continuously. There is little experience and little justification to use these methods on regular basis.
5. Induction of labour By blocking the relaxant action of progesterone on uterus of late pregnancy, mifepristone can promote labour. It may be tried in cases with intrauterine. foetal death and to deliver abnormal foetuses.
Is mifepristone a steroid?
No,mifepristone is a non steroidal drug.Mifepristone is a 19-norsteroid with potent anti progestational and significant antiglucocorticoid,antiandrogenic activity
What are the risks of taking mifepristone?
Anaemia
Dizziness
Back pain
Abdominal pain
Diarrhoea
Abdominal cramps
Low or decrease haemoglobin count
Swalling of tounge
Swelling of lips
May be allergy
symptoms after taking mifepristone.what will happen after taking mifepristone.mifepristone and misoprostol combination brand name
All questions are described above...
