The Food and Drug Administration swept away decades of controversy yesterday by approving the drug Depo Provera for use as an injectable contraceptive that gives three months of birth control with each shot.
Immediately, family planning doctors hailed the action, predicting that it will be embraced by hundreds of thousands of U.S. women eager for a long-term contraceptive that requires no maintenance except a new injection every 90 days.
"I think it's a tremendous step forward," said Dr. Edward Wallach, chairman of obstetrics and gynecology at the Johns Hopkins School of Medicine. "It is extremely effective. It has been used extensively in other countries and is very safe."
Dr. Michael Policar, national medical director for the Planned Parenthood Federation of America, said he thinks Depo Provera will be embraced by at least as many women as the half-million using Norplant, a contraceptive implant that gives five years of protection.
Norplant comes in six matchstick-sized tubes that are inserted side-by-side under the skin of the arm. Depo Provera is injected into the muscle of the arm or buttocks, where it is released into the bloodstream to prevent pregnancy.
"It's basically Norplant without walls," Dr. Policar said. "It's an incredibly effective method of birth control. It's close to surgical sterilization in terms of effectiveness rates."
Both drugs are thought to be more than 99 percent effective -- meaning they allow less than one unplanned pregnancy for every 100 users each year.
Although Depo Provera has been used as a contraceptive for as long as 25 years in 90 countries around the world, it was repeatedly denied approval in the United States amid fears that it causes benign breast tumors that could be precursors to cancer.
Those fears were based on tests performed in the 1960s on beagles, a species prone to breast tumors. But a series of studies initiated in the late 1970s by the World Health Organization showed the cancer risk to be minimal, no greater than that associated with birth control pills.
In June, a federal advisory panel unanimously recommended that the drug be cleared for contraceptive use, saying years of use abroad had provided strong evidence of its safety. Although kept off the U.S. contraceptive market until yesterday, the drug has been used for many years by patients with advanced uterine cancer.
Less widely, it has been used for the "chemical castration" of male sex offenders -- suppressing their sex drive.
The most common side effects are menstrual irregularities, weight gain and breast tenderness -- side effects also associated with Norplant. Both drugs contain synthetic versions of progesterone hormones.
Oral contraceptives, which must be taken every day to remain effective, cause menstrual cycles to become regular, which in turn gives reassurance of their effectiveness.
"That's why I don't think either method [Norplant or Depo Provera] will replace the pill," Dr. Policar said. The oral contraceptive is being used by an estimated 10 million women in the United States.
Dr. George Huggins, chief of obstetrics and gynecology at the Francis Scott Key Medical Center, said women who want long-term protection can now choose whether they want three months of protection with Depo Provera or five years of protection with Norplant.
Cost will also be an issue.
Norplant costs between $400 and $700, including a doctor's examination. The maker of Depo Provera, Upjohn Corp. of Kalamazoo, Mich., has not announced how much it will charge for each dose. But some doctors have predicted it will cost $25 to $30 for each injection after the first one, which will cost more because of the need for a full examination and medical history.
That could make Depo Provera more attractive for women who want only a few months or a year or two of protection.
"There's one extremely important caveat," said Dr. Policar. Once Norplant is removed, fertility returns within a few weeks, he said. But Depo Provera can remain effective anywhere from three months to nine months, so a couple wanting to conceive a child may have to wait longer.
Dr. Policar predicted that Depo Provera will be favored by women who have completed childbearing but do not want anything as final as surgical sterilization. Also, he said, it can be used safely on women who have had blood clots in their legs.
Doctors are not supposed to prescribe oral contraceptives for women with histories of clots.
The package insert for Depo Provera will also contain a precaution against prescribing the drug to women who have had such clots. But Dr. Policar said that precaution is based on past experience with birth control pills that contain estrogen, a hormone that can cuase clots to form.
"Medically, we know that's absolutely not the case with Depo Provera," Dr. Policar said. "Birth control pills contain estrogen, and it's the estrogen that causes the blood clots."