EMERGENCY CONTRACEPTION

 EMERGENCY CONTRACEPTION

Emergency contraception (EC) is defined as contraception that is implemented after intercourse. Women can use EC to prevent pregnancy following unprotected intercourse, which can result from sexual assault, contraceptive failure (e.g., broken condom), or other reasons.

Safe and effective methods of EC have been available for decades. However, products marketed specifically for EC are relatively new. In the United States, nearly 50% of women ages 15 to 44 years report having had at least one unintended pregnancy. Among teenagers, 88% of pregnancies are unintended. Of the 6 million pregnancies that occur each year, about 3.5 million are accidental.

Every year, unintended pregnancies lead to 1.4 million abortions and 1.1 million births that women did not want—at least not yet. Clearly, if EC were used widely, most abortions and unwanted births could be avoided.

EC can be accomplished in two basic ways:Taking an emergency contraceptive pill (ECP), also known as a morningafter pill,

or inserting a copper-T intrauterine device (IUD). Taking an ECP is most common. Furthermore, of the three basic types of ECPs—progestin-only pills, ulipristal-containing pills, and estrogen/progestin pills—the progestin-only pills are used most widely.

Progestin-Only ECPs

Three progestin-only products are available: Plan B One-Step, Next Choice One Dose, and Next Choice. All three contain levonorgestrel. These products are packaged and marketed specifically for emergency contraception. This contrasts with the estrogen/progestin products, which are marketed as oral contraceptives (OCs), but can be used off-label for EC.

Plan B One-Step and Next Choice One Dose

Plan B One-Step and Next Choice One Dose consist of a single high-dose (1.5-mg) tablet of levonorgestrel, a progestin found in many combination OCs.

The package insert calls for taking the tablet within 72 hours of unprotected intercourse. However, although early implementation is best, Plan B One-Step, Next Choice One Dose, and other ECPs can still be effective when started up to 5 days after intercourse.

Success is indicated by onset of menstrual bleeding in about 21 days. Plan B One-Step reduces the odds of pregnancy by 89% and Next Choice One Dose prevented 84% of expected pregnancies, which is better than it may seem. In the absence of these two medications, the pregnancy rate from a single act of unprotected intercourse is about 8% (i.e., 8 women in 100 would become pregnant).

However, among women using Plan B One-Step or Next Choice One Dose, only 1 and 1.3 in 100 is likely to become pregnant—a reduction of 89% and 84%, respectively.

Plan B One-Step and Next Choice One Dose work primarily by delaying or stopping ovulation. Inhibition of fertilization may also contribute. Of note, levonorgestrel is not effective after fertilization has occurred.

The major side effects of Plan B One-Step are

heavier menstrual bleeding, nausea, abdominal pain, headache, and dizziness. Nausea can be reduced by taking an antiemetic (e.g., prochlorperazine) 1 hour before dosing. Importantly, if pregnancy does occur, having used levonorgestrel will not increase the risk of major congenital malformations, pregnancy complications, or any other adverse pregnancy outcomes. These drugs will not terminate an existing pregnancy and will not harm a fetus if present. Recall that pregnancy is defined as implantation of a fertilized egg.

Since Plan B One-Step and Next Choice One Dose act before fertilization and implantation, they cannot be considered abortifacients. Plan B One-Step and Next Choice One Dose are now available over the counter. No prescription is required. ِ

Next Choice

Next Choice consists of two 0.75-mg tablets of levonorgestrel (one-half the amount in a single Plan B One-Step or Next Choice One Dose tablet).

According to the package insert, women should take 1 tablet within 72 hours of intercourse, and a second tablet 12 hours later. However, taking both tablets at the same time is just as effective. (This is equivalent to taking 1 tablet of Plan B One-Step or Next Choice One Step.) As with Plan B One-Step and Next Choice One Dose, these ECPs can still be effective when started up to 5 days after intercourse, but are most effective when taken earlier.

Adverse effects are similar to those of Plan B One-Step and Next Choice One Dose. If vomiting occurs within 2 hours of dosing, a repeat dose may be required. Like Plan B One-Step, Next Choice can be obtained without a prescription.

Ulipristal Acetate ECP

Ulipristal acetate [Ella] is a drug that acts as an agonist/antagonist at receptors for progestin. Like levonorgestrel, ulipristal acetate prevents conception primarily by suppressing ovulation.

Despite this similarity, ulipristal acetate and levonorgestrel differ in two important ways. First, ulipristal acetate remains highly effective when taken up to 5 days (120 hours) after intercourse, whereas levonorgestrel is most effective when taken within 3 days (72 hours) of intercourse. Second, whereas levonorgestrel [Plan B One-Step, Next Choice, Next Choice One Dose] is available without a prescription, ulipristal acetate [Ella] requires a prescription for all women, regardless of age.

The dosage for ulipristal acetate is 1 tablet (30 mg), taken up to 5 days after unprotected intercourse. Principal adverse effects are headache, nausea, dysmenorrhea, and abdominal pain. If vomiting occurs within 3 hours of dosing, an additional dose may be required. ِ

Estrogen/Progestin ECPs (Yuzpe Regimen)

The Yuzpe regimen, first described in 1974 by Professor A. Alfred Yuzpe, consists of two doses of an OC that contains an estrogen (ethinyl estradiol) plus a progestin (levonorgestrel or norgestrel). The first dose should be taken within 72 hours of unprotected intercourse, and the second dose 12 hours later.

Pregnancy is prevented by interfering with ovulation, fertilization, and implantation. Like other ECPs, this regimen will not cause abortion. Compared with Plan B One-Step, this regimen is less effective (75% vs. 89%) and causes more nausea (50% vs. 13.3%)and vomiting (19% vs. 6%). However, because other ECPs are more effective, better tolerated, and more readily available, these alternatives are used infrequently.

Mifepristone as an ECP

One drug—mifepristone (RU 486)—can prevent pregnancy or cause abortion, depending on when it is taken. If mifepristone is taken within 5 days of unprotected intercours .

It well prevent pregnancy from occurring, and thus can be considered an ECP. However, if mifepristone is taken after this time, it may terminate pregnancy that has already begun, and thus can be considered an abortifacient. When used as an ECP, mifepristone is 100% effective. The drug is available in the United States but is not approved for EC.

The Copper IUD

Insertion of a copper IUD (ParaGard) within 5 days of unprotected intercourse can prevent pregnancy in most women. The method is more than 99.9% effective, allowing less than 1 pregnancy .

Iud has benefit of providing ongoing contraception for up to 10 years. Although using an IUD for EC is highly effective, the technique does have drawbacks: the IUD is expensive, not all women are candidates, and obtaining one quickly may be difficult.