Abstract

PIP: Norplant, the subdermal levonorgestrel-releasing contraceptive implant, has undergone 28 years of study, clinical trials, and use by the general population. Its great advantage over combined oral contraceptives (OCs) is that it is free of estrogen and thus acceptable for use by many women with contraindications to estrogen. Norplant has few or no apparent effects on cholesterol, phospholipid, or triglyceride levels, and there is no evidence that Norplant use increases cardiovascular risk. Norplant releases a constant dose of levonorgestrel that varies from 350 ng initially to 290 ng after 5 years of use. The levonorgestrel is released directly into the circulation, avoiding the first hepatic passage. Norplant achieves its contraceptive effect by inhibiting the positive feedback exercised by estradiol on the hypothalamus and thus reducing levels of luteinizing hormone and follicle stimulating hormone, by rendering the cervical mucus inhospitable to passage of sperm, and by altering the composition of the endometrial tissue. It has been suggested that Norplant may affect tubal motility, but no studies in support of this hypothesis have been found. Secondary effects of Norplant use include decreased secretion of gonadotropins and consequently decreased frequency of ovulation, impaired luteal function, migraine or tension headaches, and occasionally such effects as facial chloasma or alterations in libido. The most frequent complications are dysfunctional uterine bleeding and irregular staining and spotting or amenorrhea. 70% of women experience such alterations of menstrual pattern with Norplant over 5 years of use. Norplant is contraindicated for diabetic women because of possible alterations in carbohydrate metabolism. Women who use certain antiepileptic or antitubercular drugs or barbiturates that affect the action of levonorgestrel should choose a nonhormonal contraceptive method. Acute or chronic cholestatic hepatic disease is an absolute contraindication. Although studies of the effects of Norplant on breastfeeding have not conclusively demonstrated any risks, the problem of steroid transfer to the infant through the breast milk has not yet been resolved. Several studies have confirmed the contraceptive efficacy of Norplant and calculated its failure rate at 2%, which makes it the second most effective method after sterilization. The rate of ectopic pregnancy is low. The implants should be inserted under aseptic conditions similar to those observed during any surgical procedure. Once the implants are removed, the serum concentrations of levonorgestrel decline rapidly. Most of the steroid is eliminated within days. Fecundity returns in the cycle following removal. 85% of women conceive within the 1st year after removal and 95% do so within 2 years.