Hormonal Contraceptives
Implants
The US Food and Drug Administration (FDA) approved the contraceptive use of levonorgestrel implants (Norplant) in 1990. This method consists of 6 silicone rubber rods, each measuring 34 mm long and 2.4 mm in diameter and each containing 36 mg of levonorgestrel. The implant releases approximately 80 mcg of levonorgestrel per 24 hours during the first year of use, achieving effective serum concentrations of 0.4-0.5 ng/mL within the first 24 hours. The rate of release decreases to an average of 30 mcg/d in the latter years of use. Release of the progestational agent by diffusion provides effective contraception for 5 years. Contraceptive protection begins within 24 hours of insertion if inserted during the first week of the menstrual cycle. The rods are inserted subcutaneously, usually in the woman's upper arm, where they are visible under the skin and can be easily palpated.
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The mechanism of action is a combination of suppression of the LH surge, suppression of ovulation, development of viscous and scant cervical mucus to deter sperm penetration, and prevention of endometrial growth and development.
Efficacy
The contraceptive efficacy of the method is equivalent to that of surgical sterilization. Overall, pregnancy rates increase from 0.2% in the first year to 1.1% by the fifth year.
Advantages
The longevity of its effectiveness is an advantage. Its effectiveness is not related to its use in regards to coitus. Exogenous estrogen is absent. Prompt return to the previous state of fertility occurs upon removal. No adverse effect on breast milk production occurs.
Although the intrauterine device (IUD) is a highly effective method of contraception, it is used by less than 2% of American women of reproductive age. The reason for such a small percentage stems from the withdrawal of FDA-approved IUDs in the 1970s. The Dalkon Shield IUD was withdrawn because of a series of litigations related to septic abortion deaths. The manufacturers withdrew their product because the cost of defending the lawsuits was deemed too expensive.Until as recently as 2000, the only 2 IUDs available in the United States were the Copper T380 (Pregna International; Mumbai, India) and the progesterone-releasing form, Progestasert (Alza; Mountain View, Calif). In December 2000, the FDA approved another form of IUD, the levonorgestrel intrauterine system termed Mirena (Berlex Laboratories; Montville, NJ). More than 2 million women in Europe have used this form of contraception in the past decade with great success.
