Health officials on Friday approved a new, longer-lasting "morning-after" pill to prevent pregnancy after unprotected sex.
The prescription drug, called ella, is made by French company HRA Pharma and will be sold in the United States by Watson Pharmaceuticals.
It is the first emergency contraceptive approved since a five-year battle under the Bush administration ended with limited over-the-counter sales and age checks by pharmacists for a rival pill.
Ella has been shown to prevent pregnancy for up to five days after unprotected sex.
The Food and Drug Administration said it cleared ella based on two clinical trials that showed the drug was safe and effective. The drug "is not intended for routine use as a contraceptive," the FDA said in a statement.
Watson said it planned to launch ella in the fourth quarter of 2010. The company has not announced a price.
The drug will compete with Teva Pharmaceutical Industries Ltd's Plan B, which works for up to three days after intercourse. Plan B is available without a prescription for those aged 17 and older, but ella will require a prescription for all ages.
Plan B, first cleared as a prescription drug in 1999, saw dozens of medical and other groups push for over-the-counter use starting in 2001. The Bush administration approved limited "behind-the-counter" sales in 2006.
Watson sells a generic version of Plan B called Next Choice.
While morning-after pills have not been huge money-makers, they have generated controversy, especially in the United States.
Sex, birth control and abortion are perennial political hotbeds even though emergency birth control drugs had been available for decades.
Conservatives, Republicans and other critics have said making another morning-after pill available — one that works even longer after sex — will further promote promiscuity. They also question ella's safety and say the drug is more akin to an abortion pill than birth control.
"The FDA opted against including the critical fact that ella can cause an abortion on a baby already implanted in its mother's womb in the drug labeling information," Jeanne Monahan, director of the Center for Human Dignity at the Family Research Council, said in a statement.
Women's groups, Democrats and other advocates say the pills offer women much-needed options to plan their families and provide a safety net when other birth control methods fail or women are raped.
"Every woman deserves every option available to prevent an unplanned pregnancy, and there are many reasons why a woman may face the risk of unintended pregnancy — from failure or improper use of birth control, to sexual assault," Cecile Richards, president of Planned Parenthood Federation of America, said in a statement.
Ella is a type of selective progesterone receptor modulator, making it part of a class of drugs that interfere with the hormone progesterone that is crucial for pregnancy. The class also includes the abortion pill known as RU-486, or mifepristone, and sold as Danco Laboratories' Mifeprex.
Watson said the overall pregnancy rate for women who took ella within three days of sex was 1.9 percent, lower than the anticipated rate of 5.6 percent. For women who took the drug two days to five days after sex, the pregnancy rate was 2.2 percent, lower than an expected rate of 5.5 percent.
Company officials and the FDA have said ella appears to work primarily by preventing the release of a woman's egg for up to five days after unprotected sex, although the lining of the uterus is also affected.
Common side effects with ella include nausea, headache and abdominal pain, according to the company's clinical data.
Women with known or suspected pregnancy and women who are breast-feeding should not use ella, the FDA said.
Known chemically as ulipristal, the drug already is sold in several European countries under the name ellaOne. HRA Pharma has said it has also begun seeking approval in other countries.