Clinical Review

UPDATE ON CONTRACEPTION

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References

WHAT THIS EVIDENCE MEANS FOR PRACTICE

Greater availability and less restrictive access to EC has not reduced the rate of unintended pregnancy in the United States. However, improvements in the counseling of women may have an impact on the pregnancy rate. As the National Survey of Family Growth reveals, only about 3% of women receive any counseling about EC in a given year. For utilization of EC to increase, women need to be aware that it exists. Providers must begin to change their practices and discuss EC at all routine appointments before the public health benefit of a decrease in unintended pregnancies can ever be realized.

Ulipristal acetate makes its debut—and demonstrates superiority to LNG

Glasier A, Cameron S, Fine P, et al. Ulipristal acetate versus levonorgestrel for emergency contraception: a randomized non-inferiority trial and meta-analysis. Lancet. 2010;375:555(9714)–562.

Fine P, Mathe H, Ginde S, et al. Ulipristal acetate taken 48–120 hours after intercourse for emergency contraception. Obstet Gynecol. 2010;115(2pt1):257–263.

In 1998, the first-generation antiprogestin mifepristone was approved for use in France in medical abortion. As early as 1991, researchers were already investigating mifepristone as a method of EC, with great success.5,6 Overall, mifepristone was more effective and had fewer side effects than oral LNG, although the onset of menses was delayed with mifepristone.7 Mifepristone is available as EC in Russia and China, but its use in other countries is limited by social and political constraints.

Enter ulipristal acetate (UPA), a second-generation progesterone receptor modulator. Unlike its predecessor mifepristone, UPA (brand name, ella) is not approved for pregnancy termination, and no studies have been performed to evaluate the effects of UPA on an existing pregnancy. Because effects on pregnancy are unknown, the manufacturer states that exclusion of pregnancy is a requirement before UPA can be prescribed for EC.

The data on UPA as emergency contraception

UPA has been evaluated for EC in two large randomized trials.8,9 In the first study, UPA was administered in a 50-mg dose as long as 72 hours after unprotected intercourse. In the second study, conducted by Glasier and colleagues, a 30-mg micronized dose (bioequivalent to the 50-mg nonmicronized dose) was used as long as 120 hours after unprotected intercourse. Participants in both studies were randomized to UPA or oral LNG.

The first study showed UPA to be at least as effective as LNG in preventing pregnancy when taken within 72 hours after unprotected intercourse. The efficacy of UPA did not appear to decline even when it was taken 48 to 72 hours after unprotected intercourse, unlike the efficacy of LNG.

The second study similarly found UPA to be non-inferior to LNG. Although neither study was powered to demonstrate superiority, both did show that UPA seemed to prevent more pregnancies than LNG.

Glasier and colleagues then performed a meta-analysis of both studies, demonstrating that UPA almost halved the risk of pregnancy, compared with LNG, in women who received treatment within 120 hours after intercourse, with a reduction of almost two thirds when UPA was taken within 24 hours of unprotected intercourse.

UPA has FDA approval for use within 120 hours after unprotected intercourse and requires a prescription. Although the data leading to this approval are incredibly encouraging, fewer than 200 of more than 2,000 women in three studies performed with UPA took EC 96 to 120 hours after intercourse. With such a small number of women actually tested in this time range, physicians should use caution when counseling patients about the efficacy of UPA when it is taken more than 96 hours after unprotected intercourse.8-10

UPA is more expensive than LNG, which may be a barrier to use by some women. However, because the probability of becoming pregnant when taking UPA within 120 hours of unprotected intercourse is lower than with LNG, the cost differential between drugs is much smaller when total costs—including the cost of unintended pregnancy—are consid-ered.11

WHAT THIS EVIDENCE MEANS FOR PRACTICE

Although the LNG-only method is the only EC that is available without a prescription, UPA appears to be more effective, particularly when it is taken more than 72 hours after unprotected intercourse. However, providers should be aware that a relatively small number of women have been studied with UPA beyond 72 hours after unprotected intercourse.

Although LNG-only EC is available behind the counter, the superiority of UPA means that physicians should discuss EC with patients during routine appointments and consider advance provision. For patients, cost and access will be important issues when deciding whether to use LNG or UPA.

EC is more likely to fail in overweight and obese women

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