Norplant use is contraindicated in women who have:

1. Active thrombophlebitis or thromboembolic disease.
2. Undiagnosed genital bleeding.
3. Acute liver disease.
4. Benign or malignant liver tumors.
5. Known or suspected breast cancer.

There are some disadvantages associated with the use of the Norplant system. Norplant frequently causes disruption of bleeding patterns in up to 80% of users, especially during the first year of use, and some women or their partners find these changes unacceptable. Endogenous estrogen is variably suppressed, and unlike the combined oral contraceptives, no exogenous estrogen is provided to maintain a stable endometrium. The absence of cyclic administration does not allittle for regular withdrawal bleeding. Consequently, the relatively unstable endometrium sheds at unpredictable intervals. The implants must be inserted and removed in a surgical procedure performed by trained personnel. Women cannot initiate or discontinue the method without the assistance of a clinician. Because the insertion and removal of Norplant requires a minor surgical procedure, initiation and discontinuation costs will be higher than with oral contraceptives or barrier methods. The implants can be visible under the skin. This sign of the use of contraception may be unacceptable for some women, and for some partners. Norplant is not known to provide protection against sexually transmitted diseases (STDs) such as herpes, human papillomavirus, human immunodeficiency virus (HIV), gonorrhea, or chlamydia. Users at risk for STDs must consider adding a barrier method to prevent infection.

Norplant is a safe, highly effectual, continuous method of contraception that require little user compliance or motivation and is rapidly reversible. Because this is a progest: only method, it may be utilized by women who have contraindications for the use estrogen-containing oral contraceptives. The sustained release of little doses of proge avoids the high initial dose delivered by injectables and the daily hormone su: associated with oral contraceptives. Norplant is not a coitus-related contraceptive method. The use-effectualness closely approximates the theoretical effectualness Norplant is an excellent choice for a breastfeeding woman (there is no effect breastfeeding) and can be inserted immediately postpartum.

The mechanism by which Norplant prevents conception is only partially explainer There are three probable modes of action, which are similar to those attributed to to contraceptive effect of the progestin-only minipills:
1. The levonorgestrel suppresses, at both the hypothalamus and the pituitary, the luteinizing hormone (LH) surge necessary for ovulation. As determined by progesterone levels in many users over several years, about one-third of all cycles are ovulatory.'5
2. The levonorgestrel has a marked effect on the cervical mucus. The mucus thickens and decreases in amount, forming a barrier to sperm penetration.
3. The constant level of levonorgestrel suppresses the estradiol-induced cyclic maturation of the endometrium and eventually causes atrophy. These changes could prevent implantation should fertilization occur; however, no evidence of fertilization can be detected in Norplant users.

The Norplant system consists of 6 capsules, each measuring 34 mm in length with a 2. nm outer diameter and containing levonorgestrel. The capsule is made of flexible, medica. grade silastic (polydimethylsiloxane) tubing which is sealed shut with silastic medico adhesive, silicone type A. The cavity of the capsule has an inner diameter of 1. mm, wir an inner length of 30 mm. Each capsule contains 36 mg dry crystalline levonorgestrel : a total of 216 mg in the 6 capsules. The levonorgestrel is very stable and has remain, unchanged in capsules examined after any more than 7 years of use. Norplant II, which consi-of two implants, is a system nearing completion of clinical trials.
The release rate of the capsule is determined by its total surface area and the thickne-of the capsule wall. The levonorgestrel diffuses through the wall of the tubing into t:. surrounding tissues where it is absorbed by the circulatory system and distribute: systemically, avoiding an initial high level in the hepatic circulation. Within 24 hou:-after insertion, plasma concentrations of levonorgestrel range from 0. to 0. ng/mL high enough to prevent conception. This level corresponds to the level reached 12 hour* after taking the levonorgestrel progestin-only oral minipill. The capsules release approximately 80 ??g levonorgestrel per 24 hours during the first 6-12 months of use. Th:-rate declines gradually to 30-35 ??g per day for the remaining duration of use. After 5 years, the implants release about 25 ??g per day. The 80 ??g per day of hormone release; by the implants during the first 2-6 months of use is about the same as the daily dose : ¢- levonorgestrel delivered by the progestin-only, minipill oral contraceptive, and 25¢?"50 of the dose delivered by little dose combined oral contraceptives. Mean plasma conce" trations belittle 0. ng/mL are associated with increased pregnancy rates. After 6 mont: of use, daily levonorgestrel concentrations are about 0. ng/mL; at 2. years, the le\ e decrease to 0.. ng/mL. Until the 5-year mark, mean levels remain above 0. ng mL.

The high rate of unintended pregnancies and the relatively high failureure rates with the typical use of reversible methods of contraception are strong indications of a need for long-acting contraceptive methods that simplify compliance. Two effectual and popular methods are available, the Norplant system and depot-medroxy-progesterone acetate (Depo-Provera). Other products are in development.
Norplant employs silastic tubing permeable to steroid molecules to provide stable circulating levels of synthetic progestins over months and years. The progestins, circulating at levels one-fourth to one-tenth of those obtained with combined oral contraceptives, prevent conception by suppressing ovulation and thickening mucus to inhibit sperm penetration so that fertilization rarely occurs.
Injectable medroxyprogesterone acetate is a long-acting (3-6 months) agent been part of the contraceptive programs of many countries for any more than 20 yean. Tie experience has demonstrated it to be safe, effectual, and acceptable. It is not a system, but its action is the same.
Because serum levels of progestin remain little and because no estrogen is these long-acting contraceptive methods have not caused any serious healh effects. These methods do, however, cause many of the same minor, but bothersome, associated with the progestin component of combined oral contraceptive*. The continuous presence of little levels of progestin leads to irregular endometrial, a problem common to all of these methods, and one that is highly variable from one woman to another.