Norplant: Birth Control at Arm's Reach

by Food and Drug Administration (FDA)

The newest birth control option for women is literally at arm's reach. The Norplant contraceptive, approved by the Food and Drug Administration last December and marketed since February, is implanted just under the skin of the inner arm, right above the elbow. Developed by the Population Council of New York, this birth control alternative is distinctly different from methods previously available.

New Form, Old Content

Norplant consists of a familiar ingredient in a new package. Six silicone rubber capsules about the size of matchsticks contain a synthetic progestin hormone long used in birth control pills. The flexible tubes are inserted in a fan-like arrangement and can be felt but not easily seen.

Once in place, they steadily release a low dose of hormone into the bloodstream. Effective within 24 hours after insertion, Norplant can continue to prevent pregnancy for up to five years.

The hormone usually inhibits ovulation so that eggs are not produced regularly, and causes the mucus of the cervix to thicken, making it more difficult for sperm to reach the egg. Other ways that Norplant may provide contraceptive effects have been proposed but not proven.

Experimental Attitude

Jennifer Collier, a 28-year-old New York law student, entered a study of Norplant at the Robert Wood Johnson Institute in New Brunswick, N.J., in the spring of 1984 and is now on her second implant, inserted last June.

"It sounded like a really neat invention, so I decided to try it," says Collier. She had been dissatisfied with the weight gain and irritability she experienced using oral contraceptives. With Norplant, she says, she isn't troubled with either of those side effects. Collier describes the implant as visible, "but not terribly obvious. No one has noticed it unless they were looking for it, probably partly because of where it's inserted."

Each Norplant capsule is 2.4 millimeters (about one-tenth of an inch) in diameter and 34 millimeters (just under one-and-a-half inches) long, and holds 36 milligrams of powdered crystals of the progestin levonorgestrel. The tubes are made of Silastic, a silicone material long used in surgical implants such as heart valves and hip joints.

The hormone seeps through the permeable tubes into the bloodstream, initially at a rate of about 85 micrograms a day. The amount declines gradually to about 50 micrograms by nine months, 35 by 18 months, and about 30 micrograms at the end of five years. In comparison, birth control pills that contain levonorgestrel provide about 50 to 150 micrograms of the progestin a day, plus estrogen. (The only progestin-only contraceptive available in the United States contains 75 micrograms of norgestrel, a progestin similar to levonorgestrel.)

When the hormone supply dwindles, usually in about five years, a new implant can be inserted if desired. On the other hand, if a woman wishes to become pregnant earlier, she can have the implants removed at any time, and fertility is restored very soon. Blood levels of the progestin are undetectable within 5 to 14 days.

Population Council Project

Norplant has been marketed in other countries for several years. According to the Population Council, more than half a million women in 46 countries have used the implant since it was first approved in Finland — where it is manufactured — in 1983. It now has regulatory approval in 17 other countries as well, including Sweden, Indonesia, the Dominican Republic, Thailand, China, Peru, and the United States. Norplant's U.S. distributor is the Philadelphia-based pharmaceutical firm Wyeth-Ayerst Laboratories.

"The first implants were tested in 1968," says Population Council vice president Wayne Bardin, M.D., "and then the council began to develop and test implants that released a whole variety of progestins. By 1974, we came up with what is now the Norplant implant, using levonorgestrel. The first clinical trial of that was begun in 1975."

FDA approval of the implant was based on the results of clinical studies involving 2,400 women in the United States, Finland, Sweden, Denmark, Jamaica, Brazil, Chile, and the Dominican Republic.

In the studies, the contraceptive's effectiveness approached that of sterilization in the first year. (See chart below or whatever.)

Pregnancy rates were slightly higher in heavier women, increasing after the third year of use in those who weighed more than 69 kilograms (153 pounds). Nevertheless, the protection is still quite good. For example, among 100 women of all weights using the implant for five years, it is expected that four would become pregnant during that time. By contrast, of 100 women using the pill for the same time, at least 15 might be expected to become pregnant.

Norplant's effectiveness does not depend on patient compliance — a feature shared by only one other type of reversible contraceptive — the intrauterine device, or IUD. This particularly appeals to Collier for the convenience it affords. "Unlike the pill, you don't have to remember to take it every day, and, unlike the diaphragm, there's no problem with spontaneity," she says.

Because Norplant is not a barrier contraceptive, however, it offers no protection against sexually transmitted diseases such as AIDS, herpes, chlamydia, and gonorrhea. For optimum protection from both disease and pregnancy, couples may choose to use both Norplant and a condom.

The Drawbacks

As with virtually any drug or medical device, Norplant isn't entirely trouble-free. Side effects that women have reported with the implant during the first year include irregular menstrual bleeding, headache, nervousness, depression, nausea, dizziness, skin rash, acne, change of appetite, breast tenderness, weight gain, enlargement of the ovaries, and excessive growth of body or facial hair.

Some Norplant users have also reported breast discharge, vaginal discharge, inflammation of the cervix, abdominal discomfort, and muscle and skeletal pain. These effects, however, cannot be linked to use of the implant because the complaints are common among the general population and could stem from many other causes. There is no known biological reason to link the complaints specifically to use of the contraceptive.

By far, the most common side effect is menstrual cycle irregularity. "To give the percentage of women with menstrual irregularities is complex," says Bardin, "because it changes with time." He says that over a five-year period of use, about 45 percent of women will have irregular periods and another 45 percent will have normal periods. The remaining 10 percent will have long periods of time — three to four months — with no bleeding. "That's an average," says Bardin. "Basically what happens is you have more women with irregular periods in the first year and that tends to diminish with continuing use."

The bleeding irregularities result from the continuous hormone release. "With the oral contraceptive pills, estrogen and progestin are taken for three weeks and withdrawn for one week, causing regular bleeding," explains Lisa Rarick, M.D., a medical officer in FDA's division of endocrine and metabolism drug products. "Norplant, on the other hand," says Rarick, "provides no cyclic withdrawal, and thus each individual creates her own bleeding pattern."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.