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  • Title: Innovations in contraception: the Norplant system.
    Author: Klaisle CM, Wysocki S.
    Journal: NAACOGS Clin Issu Perinat Womens Health Nurs; 1992; 3(2):267-79. PubMed ID: 1596435.
    Abstract:
    The Norplant (Huhtamaki Oy/Leiras Pharmaceuticals, Turku, Finland) contraceptive system is a safe, highly effective, reversible method of hormonal contraception. The system consists of six flexible match-size implants that are implanted in the inner aspect of the upper arm. This sustained-release system delivers the progestin levonorgestrel at levels sufficient to prevent pregnancy for as long as 5 years. Norplant is a convenient, easy-to-use method. Adequate counseling of potential users and appropriate selection of patient users are important determinants of patient satisfaction with Norplant. The Norplant implant is described: the release rates and serum levels of levonorgestrel, the mode of action, the indications and contraindications, the effectiveness, incidence of ectopic pregnancy related to Norplant use, metabolic effects, advantages and disadvantages, insertion, the role of counseling, and management of side effects (menstrual bleeding changes, headache, weight changes, mastalgia, and acne), continuation rates and reasons for termination, and removal. Norplant is currently the most effective method of contraception. Counseling is important in order to provide women with as much information for informed consent and to increase awareness and interest in Norplant. In a clinical trial in California, 95% expressed a high level of satisfaction upon implant removal and 71% desired Norplant again; 91% recommended Norplant to friends. 82% reported the side effect of menstrual change; 66% reported 2 or more side effects. Clinical development is ongoing for other sustained release contraceptives. Norplant was developed by the International Committee for Contraceptive Research of the Population Council, and manufactured by Huhtamaki Oy/Leiras Pharmaceuticals in Turku, Finland. Clinical trials have been conducted since 1975. 20 nations have approved its use, and more than 1.5 million women use it. Silastic rubber tubing encapsulates 6 capsules of 36 mg/capsule crystalline levonorgestrel, a strong progestin. Implantation is done just under the skin in a fan shape; levonorgestrel is released at 80 mcg/day for 6 months, and 30-35 mcg/day for the remainder of use. The mode of action is not completely understood, but the assumption is that it is similar to the progestin-only pills. The mechanisms that alter fertility are 1) the change in hypothalamic-pituitary level to inhibit midcycle luteinizing hormone surge, while follicle stimulating hormone and estradiol levels remain within the normal range, 2) the thickening of the cervical mucus which prevents the entry of sperm into the upper genital tract, and 3) the suppression of the estrogen-induced cyclical maturation of the endometrium. It is not an abortifacient. Contraindications are few, but include active thrombophlebitis, undiagnosed abnormal genital bleeding, known or suspected pregnancy, benign or malignant liver tumors, and known or suspected breast cancer of progestin-dependent neoplasms.
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