1) Adapted from Emergency Contraception, Current Therapeutics October 2001 by Edith Weisberg (Director of Research, Family Planning Association Health, Sydney, NSW)
2) Adapted from The Pharmaceutical journal Vol 265
Although there are many highly effective methods of contraception available none are none are 100% shows it effective. Many pregnancies are unplanned and unwanted either due to contraceptive failure or lack of contraceptive use. The risk of pregnancy with one unprotected act of sexual intercourse can be high as 30% depending on the day of cycle
That intercourse took place in relation to ovulation.
For the women exposed to unprotected sexual intercourse, example
Ø Lack of contraceptive use
Ø Condom breakage or
Ø Sexual assault
Emergency contraception or also known as postcoital contraception can be used to prevent unwanted pregnancy. Given the nature of sexual arousal couples or individuals are more likely to consider the risk of pregnancy after unprotected intercourse rather than prior to the act. Having emergency contraception could reduce the abortion rate in Australia where, 1 in 4 pregnancies ends in abortion.
ECPs should be given as soon as possible after unprotected intercourse-preferably within 24 hours. Efforts should be done to make sure that every women know about emergency contraception. It is important for women to have correct information about the ECPs regiments, mode of action, and efficacy.
Miss MELANIE OGDEN (pharmaceutical adviser, Manchester health authority) presented some of the findings of the scheme to the audience.
Over the millennium holiday period itself, there had been 36 requests for emergency contraception but numbers had increased and in July there had been 676 requests.
Women between 20 and 29 years are commonly asked for ECPs. However the range of age was from 13 to 57 years and 24% of request came from women under 19 years old. Most commonly request are made between Saturday and Monday. 27% requests are made at the weekend when the agencies were closed.
The most common reason for ECPs supply were unprotected sex and burst condoms.
Women at the age under 19, were those who usually presented because of unprotected sex.
50% of women will be menstruate at the expected time after hormonal emergency contraception.
For the remainder their menstrual period should occur within 1 week before after the expected time. If menstruation is delayed for more than 1 week or it is much lighter than normal, emergency contraception may have failed and the women should have pregnancy test.
The use of regular contraception should not being replaced by ECPs, as the cumulative pregnancy rate for frequent use of ECP is higher than regular contraception.
However , if unprotected intercourse occurs in a cycle where the ECP has already been used, it can be used again. Women should understand since the use of ECP can delay ovulation. There is a possibility pregnancy from unprotected intercourse later in the cycle.
Therefore, contraception such as, condoms should be used with a subsequent episodes of intercourse. Women who choose to use oral contraceptives for ongoing contraception after taking ECP can start their pill the day after their second ECP dose.
They do not need to wait for the first day of their next period. In a cycle where the ECP has been taken and a combined pill started immediately following this, the next period will be delayed as it will be a withdrawal bleed following used of the combined pill.
It is wise to check that the ECP has been effective by doing a pregnancy test 1 week after the natural period was due.
In cycles where unprotected intercourse has occurred more than once, ECP can be used provided it is not more than 72 hours after unprotected intercourse. Although ECPs can be given more than 72 hours after unprotected intercourse, their effectiveness considerably reduced as the interval following intercourse increases. If pregnancy has already occurred as a result of unprotected intercourse ealier in the cycle, the pregnancy will not be aborted nor will there be an increased of teratogenesis as a result of taking the ECP.
The exact mode of action for all the methods of ECPs is not completely understood.
If given prior to ovulation they may inhibit or delay ovulation. They may also interfere with ovum and sperm transport, fertilization and implantation. ECPs will not dislodge the embryo after implantation has occurred; they for they do not cause an abortion.
The efficacy rate of ECPs were shown by the percentages of pregnancies prevented versus the expected number of pregnancies that would occur without unprotected intercourse relative to the cycle day on which this took place. The Yuzpe method reduce the risk of pregnancy after a single unprotected act of sexual intercourse by about 75% and the Levonorgestrel-only regiment and Mifepristone by about 85%.
This is mean that if woman has 8% probability of pregnancy after unprotected sex, these regimens would reduce probability to about 2% or 1% respectively.
With both regimens the efficacy is higher the sooner they are started after unprotected sexual intercourse.
With the Yuzpe method, the pregnancy rate is 2% if started within 24 hours and 4.7% if it is started 72 hours.
The rate for Levonorgestrel regimen is 0.4% within 24 hours and 2.7% within 72 hours.
For every 12 hours period that elapses between unprotected intercourse and taking of the first dose of an ECP, the risk of failure are doubles.
The Yuzpe method is a high dose regimen of combined oral contraceptives containing theoestrogen, ethinyl oestradiol and the progestogen, levonorgestrel. The dose of levonorgestrel (500µg) is as essential as the dose of ethinyl oestradiol (100µg) to make sure maximum effectiveness. It can be either prsescribed as two 50µg ethinyl oestradiol/250µg levonorgestrel pills (Nordette 21 or 28 Microgynon 30), taken as soon as possible within 72 hours of unprotected intercourse, followed by the same dose 12 hours later.
A regimen of 750µg levonorgestrel taken as soon as possible within 72 hours after unprotected intercourse, with a second dose 72 hours later appears to be more effective and has fewer side effects than the Yuzpe regimen.
The levonorgestrel mini-pill (Microlut, Microval; contains 30µg levonorgestrel) can be used instead; 25 pills should be taken at each dose to make up the required 750µg dosage.
10 mg Mifepristone is a highly effective emergency contraceptive with fewer side effects than the Yuzpe method had been indicated by WHO multi centre. It san be given successfully up to 5 days after unprotected intercourse. A minor draw back is that about 20% of users will have a delay in the onset of he next menses. Women will need to be warned about this and continue use of a contraceptive method until bleeding starts of a pregnancy is confirmed.
At present it is unlikely that mifepristone will be available in Australia. A change to the therapeutics Good Act made it mandatory that any drug such as RU 486 that could be used as abortofactient, even if it was being marketed for another indication, had to have the signature of the Minister for health and be notified to the Parliamentary Secretary, as well as undergoing the normal channels of drug evaluation.
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