Implants (birth control)

Implants, like the oral contraceptives, are based upon the administration of hormones and grew out of the same research. Research on an implantable contraceptive began in 1966, although it was not until 1974 that clinical trials were undertaken on a variety of progestins. The trials led to the decision to use levonorgestrel as the form of progestin for the new implants. The most widely known of the early implantables was Norplant, which, after undergoing a series of trials, was recognized as acceptable by Finland. Gradually other nations followed and in 1990 the U.S. Food and Drug Administration approved its use. Norplant is distributed by Wyeth-Ayerst Laboratories.

Under the Norplant system, six flexible capsules (originally they were hard), each about the size of a paper match, are placed just under the skin of a woman’s upper arm. Each capsule contains 36 mg of levonorgestrel in crystalline form, and each capsule releases approximately 85 micrograms (mcg) per day, decreasing to 50 mcg per day by nine months, 35 mcg per day at eighteen months, and then 30 mcg per day for the third, fourth, and fifth years. The capsules are timed to release the contents over a five-year period, and for the first year only one woman in every five thousand becomes pregnant.The possibility of pregnancy increases as the Norplant insert ages, but it is still very low. There is a higher failure rate for heavier women (more than 154 pounds) than for those less heavy, but the failure rate has decreased with the use of soft capsules, now the norm.

The best time to insert the implant is when a woman is menstruating but certainly not later than five to seven days after the menses have begun. This ensures that the woman is not preg-nant.The skin is infiltrated with a local anesthetic (usually lidocaine) where the implantation is to take place and then a small incision about an inch long is made and the capsules are implanted in an operation that lasts about ten minutes. The incision is covered with a dressing for three to five days. Insertion is not particularly painful for most women. For some, the implants may be visible. Removal of the implants is more difficult than insertion; the same procedure is used but it takes a little longer to locate and extract the implants. If there is not too much swelling or trauma, new capsules can be inserted to replace the old ones.

Implants eliminate the inconvenience of taking pills, positioning intrauterine devices, or inserting spermicides. They are also less expensive than oral contraceptives are and release hormones at a regular, even interval. Because they contain no estrogen, implants do not have any cardiovascular side effects. Infertility is reversed by removing the implants. All study patients ovulated within seven weeks after the implants were removed.Also, the implants can be used by women who breast-feed. Norplant II, an improved version, uses two rods instead of six.

Other inserts have since entered the market. Carpronor, developed by the Research Triangle Institute in North Carolina, also uses lev-onorgestrel. Carpronor is inserted under the skin of the arm or the hip and is effective for eighteen to twenty-four months.The Population Council developed a progestin and cholesterol pellet of 10 percent cholesterol and 90 percent norethindrone. The pellet is about the same size as a grain of rice and is biodegradable within twelve to eighteen months.

Dr.Wayne Bardin, vice president f the Population Council, holds implants, which when injected into a woman's arm release levonorgestrel, prohibiting conception for a period of up to five years.

Dr.Wayne Bardin, vice president f the Population Council, holds implants, which when injected into a woman’s arm release levonorgestrel, prohibiting conception for a period of up to five years.

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