WASHINGTON — A Food and Drug Administration advisory committee voted unanimously Thursday to recommend approval of a long-acting contraceptive that protects a woman from pregnancy for five years when implanted under the skin in the form of six silicone rubber capsules the size and shape of wooden match sticks.
Final FDA approval of Norplant, which contains the same progesterone-like hormone in many birth control pills, could come in the next several weeks. Implants could become available to American women six months after approval.
The 11-member committee found that the new contraceptive is both highly effective and at least as safe as birth control pills already on the market. "I think we could say safer," said committee member Paul G. McDonough, a professor of obstetrics and gynecology at the Medical College of Georgia.
Norplant, developed by the nonprofit Population Council, is the first contraceptive to employ slow-release capsules implanted beneath the skin. It provides a constant, very low dose of the hormone levonorgestrel. It is believed to work both by inhibiting ovulation and by stimulating the cervix to produce thick, impenetrable mucus that keeps sperm from entering the uterus.
The product is already approved for use in a dozen countries. In studies of more than 55,000 women in 44 countries, Norplant's major side effect has been its tendency to cause irregular menstrual bleeding, which can range from heavy periods to spotting to the absence of periods. Between 20% and 25% of women in the studies stopped using the product within five years because of menstrual problems.
Even so, studies of Norplant's acceptance by women compare favorably with studies of pills and other methods of birth control, said Dr. C. Wayne Bardin, director of the Population Council's Center for Biomedical Research.
"It delivers the lowest dose of hormones used in any hormonal contraceptive," he said. "It does not contain estrogen, the hormone believed to be responsible for the most serious potential side effects of birth control pills, such as heart attacks and strokes. And it produces blood levels of levonorgestrel that are less than one-tenth as high as those found in women who take birth control pills."
A single dose consists of six silicone rubber capsules placed beneath the skin of the upper arm. To implant the capsules, a doctor or nurse first injects a local anesthetic, then makes a small puncture in the skin. Next, a hollow needle-like instrument is inserted through the puncture and used to guide each capsule into place.
Once inserted, the capsules can be felt through the skin but are usually not visible.