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قرصهاي لوونورژسترل Levonorgestrel 1.5 mg در بسته بندي 2تايي است و مصرف اولين قرص بعد از نزديكي در حداقل زمان ممكن تا حداكثر 72 ساعت و دومين قرص 12 ساعت بعد از قرص اول
به عنوان اورژانس پيشگيري از بارداري كاربرد دارد.
Postcoital Contraception
Levonorgestrel is used as an emergency contraceptive (EC) to prevent pregnancy following unprotected intercourse or known or suspected contraceptive failure. To achieve optimal efficacy, the first dose of the postcoital contraceptive regimen should be taken as soon as possible within 72 hours of unprotected intercourse; the second dose should be taken 12 hours later.
Some evidence indicates that a short-course, emergency contraceptive regimen employing a progestin alone (levonorgestrel) may be at least as effective as, and better tolerated than, a common estrogen-progestin emergency contraceptive (‘‘Yuzpe’’) regimen when the regimens are initiated within 72 hours of unprotected intercourse. In a double-blind, randomized, multicenter study in women who reported only one act of unprotected intercourse within 72 hours of receiving emergency contraception, the expected pregnancy (failure) rate of 8% (with no contraception) was reduced to approximately 1% with the progestin-only regimen (levonorgestrel 0.75 mg every 12 hours for 2 doses) compared with 3.2% with the estrogen-progestin (Yuzpe) regimen (levonorgestrel 0.5 mg and 0.1 mg ethinyl estradiol every 12 hours for 2 doses). In another prospective, randomized study in women who reported a single act of intercourse within 48 hours of receiving emergency contraception, failure rates with the same levonorgestrel-only and Yuzpe regimens were similar (2.6 versus 2.4%, respectively). The efficacy of treatment in both studies was greatest when the contraceptive was given during the first 24 hours after unprotected intercourse; efficacy declined during subsequent 24-hour periods. The levonorgestrel-only regimen was better tolerated than the Yuzpe regimen. In these 2 studies, nausea occurred in 23.1 versus 50.5% and in 16.1 versus 46.5% of women receiving the levonorgestrel-only versus the Yuzpe regimen, respectively, while vomiting occurred in 5.6 versus 18.8% and in 2.7 versus 22.4% of women with the levonorgestrel-only or Yuzpe regimen, respectively.
Since unprotected intercourse that occurs outside the fertile period is unlikely to result in conception, not all women given emergency postcoital contraception are at genuine risk for pregnancy. Therefore, a more accurate indication of the efficacy of postcoital contraceptive regimens would be based on the timing of unprotected intercourse and the probability that pregnancy would occur without treatment. Analysis of data from the multicenter, progestin-only (levonorgestrel) study involving approximately 2000 women suggest that when efficacy of postcoital contraception is based on the observed versus expected number of pregnancies, the levonorgestrel-only regimen would prevent 85% of pregnancies; pooled analysis of observed-versus-expected pregnancy data from other studies employing the Yuzpe regimen suggest that such therapy is approximately 74% effective in preventing pregnancy.
Since postcoital contraceptive efficacy diminishes as the time period between intercourse and administration of the regimen increases, available data suggest that as with combination estrogen-progestin regimens, progestin-only postcoital contraception should begin as soon as possible but within 72 hours of unprotected intercourse. Insufficient data are available to evaluate the effectiveness of postcoital contraception administered after more than 72 hours.
The American College of Obstetricians and Gynecologists (ACOG), other experts, and some states (e.g., Alaska, California, Hawaii, Maine, New Mexico, Washington) have advocated increased access to emergency postcoital contraception (e.g., nonprescription access via pharmacies, advance provision by clinicians) as a means of decreasing unintended pregnancy and abortion rates. There is some evidence that increased access to emergency postcoital contraception may not compromise conventional contraceptive use or sexual behavior, potentially allaying some concerns that have prompted others to advocate for restricted access. The US Food and Drug Administration (FDA) has approved levonorgestrel (Plan B®) for nonprescription (over-the-counter [OTC]) status for women 18 years of age or older; the contraceptive will remain a prescription-only preparation for women younger than 18 years of age. FDA has concluded that there are sufficient data to support the safe use of Plan B® as an OTC preparation for women 17 years of age and older. Because of difficulties envisioned by the FDA in enforcing an age-based restriction on the OTC availability of Plan B®, 18 was chosen as the cutoff age. In making this decision, FDA took into account the fact that 18 is the age considered to be the age of majority and this is the legal age for the sale of certain other products (e.g., OTC nicotine-replacement preparations, pseudoephedrine).
For information on the use of combination estrogen-progestin contraceptives for postcoital contraception, see Contraception: Postcoital Contraception under Uses, in Estrogen-Progestin Combinations 68:12.
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AHFS Drug Information. (CR) Copyright, 1959-2008, Selected Revisions January 2008. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.
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