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  • Title: NORPLANT contraceptive implants advancing.
    Author: Segal SJ.
    Journal: Netw Res Triangle Park N C; 1984; 5(3):1-3. PubMed ID: 12279797.
    Abstract:
    NORPLANT contraceptive implants, approved by the Finnish National Board of Health in late 1983, provides truly longterm protection. A single set of implants placed under the skinn of the upper arm protects a woman against pregnancy for at least 5 years. The pregnancy rate in the 1st 3 years of use is comparable to that for sterilization. Over the entire 5-year period of recommended use, the observed pregnancy rate has been 0.5/100 women per year. At any time, the implants can be removed and normal fertility restored. Clinical studies have been in process since 1968, and the testing of the specific formulation now approved began in 1974. The NORPLANT implant system consists of 6 silicone rubber (Silastic) capsules of small diameter (2.4 mm). The capsules are 34 mm long, and each contains 36 mg of levonorgestrel, a progestin in wide use as an oral contraceptive (OC). Placement and removal of the implants involve minor office surgery. A local anesthetic is infused, the skin is nicked, a trocar is used to insert the capsules, and a strip of adhesive bandage is placed over the insertion point. Placement takes about 5 minutes and removal, on the average, about 15 minutes. Diffusion of levonorgestrel from the capsules begins immediately after placement, and contraceptive effectiveness starts at once. Efficacy is maintained for more than 5 years by the continuous release of about 30 mcg of levonorgestrel per day. At the blood levels achieved, ovulation is inhibited in about 1/4 of the cycles. The high level of effectiveness must invoke other mechanisms of action. Most significantly in this regard, levonorgestrel alters the cervical mucus, rendering it highly impenetrable to sperm. In the principal clinica l tudies of the population council, the pregnancy rates are uniformly low. In separate trials in several developing countries, the observed pregnancy rates were all well below 1/100 at the end of the 1st year. The high rates of continuation of use observed in these studies suggest an important programmatic advantage of this method for national family planning programs. NORPLANT implants cause irregular menstrual bleeding in some cases. Menstrual problems are the most frequent complaint of users, and in the 1st year of use, they tend to be the most common reason for discontinuation. In recent studies the percentage of users who discontinue use during the 1st year range from 2.2-8.3. As a progestin only method, the system eliminates the risks associated with the estrogenic component of combination OCs. The nature of the implant method introduces the risk of infection at the site of placement or removal of implants. As NORPLANT implants do not block ovulation consistently, the normalcy of pregnancy, if it occurs must be considered. The reversibility of the NORPLANT contraceptive system has been established clearly.
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