On October 29, 1992, the U.S. Food and Drug Administration (FDA) approved contraceptive labeling for depot-medroxyprogesterone (DMPA); commonly known by its trade name, Depo-Provera. This culminated a twenty-year effort to make a long-acting injectable contraceptive available to American women. Based upon the findings of extensive clinical research done outside the United States over a decade, the FDA determined that while some concerns remained, DMPA was considered to be as safe as other hormonal contraceptives already on the market.
DMPA's mechanism of action is quite similar to that of all other hormonal methods of contraception: inhibition of ovulation; thickening of cervical mucus, which makes sperm penetration through the cervical mucus more difficult; and induction of endometrial atrophy, which prevents implantation in the highly unlikely event of fertilization. The chemical structure of DMPA is much closer to that of natural progesterone than that of the 19-nortestosterone progestins used in oral contraceptives and Norplant. This may account for the fact that DMPA users have little, if any, change in a number of metabolic parameters over time. In particular, there is no change in clotting factors, globulin levels, or glucose metabolism in DMPA users when compared to pretreatment levels. The slight decrease in total cholesterol levels seen in DMPA users is the result of a minor drop in high-density lipoprotein, the "good" cholesterol, although neither change is clinically significant. Interestingly, DMPA positively affects the central nervous system, causing the seizure threshold to increase, thus making seizures less likely in women with seizure disorders (e.g., epilepsy). Estrogen levels in DMPA users remain at early follicular phase levels, and while other menopausal symptoms do not occur, there is a possibility that some DMPA users may lose a small amount of bone mass over time.
With DMPA there are 0.3 failures per one hundred women during the first year of typical use. This high efficacy is due both to DMPA's efficiency in inhibiting ovulation and the fact that it is a relatively "user friendly" method of contraception. The long interval between injections, a two-week grace period for injections given beyond twelve weeks, and the absence of need for any user or partner intervention at intercourse all contribute to DMPA's high effectiveness.
DMPA is given as a deep intramuscular injection into the deltoid (upper arm) or buttocks every twelve weeks. Since administration most optimally is provided with a 11/2 inch needle, most DMPA users, particularly thin women, will prefer the buttocks site. The initial injection of 150 mg of DMPA must be given within the first five days after the onset of menses, unless the woman has effectively been using the pill or has an IUD, in which case the first injection can be given any time during the month. Subsequent 150-mg injections are given at twelve-week intervals, although pregnancy is highly unlikely during the following two-week grace period. If fourteen weeks or more have elapsed since the last DMPA injection, a negative highly sensitive urine pregnancy test must be documented before the next injection is given.
The ideal candidate for DMPA is a woman who is seeking continuous contraception; wants long-term birth spacing; desires a method that is neither coitus-dependent nor requires daily motivation; or who cannot use, or chooses not to use, a barrier method, an IUD, or an estrogen-containing method. It may be particularly appropriate for women who cannot use OCs because of a history of thrombophlebitis, hypertension, heavy smoking, or other cardiovascular risk factors. Women with sickle-cell anemia or seizure disorders actually may experience an improvement in their medical condition. DMPA is an excellent method for postpartum and post-abortal women and can be initiated immediately after completion of the pregnancy. Postpartum women who are lactating (nursing) should not be given DMPA until lactation has been established, usually one to two weeks after delivery. Women who desire a high degree of confidentiality in contraceptive use are attracted to DMPA because it does not require the personal possession of medications or devices, nor does it leave marks of administration or current use.
DMPA has few contraindications: active thrombophlebitis; undiagnosed abnormal genital bleeding; known or suspected pregnancy; active liver disease; a history of benign or malignant liver tumors; known or suspected carcinoma of the breast; and sensitivity (allergy) to the medication. Special conditions requiring more detailed medical evaluation and follow-up include a history of heart attack or stroke; diabetes mellitus; current migraine headaches; a history of severe endogenous depression; and chronic hypertension.
Menstrual changes are universal in women using DMPA and include episodes of irregular bleeding and spotting (lasting seven days or more during the first months of use) and amenorrhea (no menses). Sixty percent of women using DMPA for one year report amenorrhea, and the percentage increases with progressively longer use. Menstrual changes are the most frequent cause for dissatisfaction and discontinuation among women using DMPA, and appropriate patient education and selection and supportive follow-up measures can markedly reduce patient discontent. Medical intervention for irregular or heavy bleeding rarely is necessary, and anemia is uncommon. While counseling and reassurance are initial measures, medical therapy consisting of low-dose oral estrogen for one to three weeks may give temporary respite from bleeding. Women persistently dissatisfied may be better served by discontinuing this method and seeking alternative types of contraception rather than by repetitive medical or surgical intervention. In cases of heavy vaginal bleeding, gynecologic evaluation to rule out such unrelated conditions as vaginitis, cervicitis, or cervical lesions should be performed.
Another group of side effects that occur fairly frequently among DMPA users are pregnancy symptoms such as nausea, breast tenderness, abdominal bloating, and tiredness. While these symptoms are prevalent in the first few months of DMPA use, persistence is uncommon and they rarely are cause for discontinuation.
Weight gain occurs in two-thirds of DMPA users owing to the drug's anabolic effect and its resultant impact on appetite. On average, DMPA users gain four pounds per year for each of the first two years of use. Women concerned or dissatisfied with weight gain should be counseled that it may be controlled with adequate exercise and moderate dietary restriction. Many women notice weight stabilization or improvement with time. If these measures fail and weight gain becomes problematic, DMPA discontinuation may become necessary.
Headache is a relatively common complaint in DMPA users, although not all headaches are necessarily related to the hormone in the drug. If the headaches are mild and without neurologic changes, treatment may be attempted with oral analgesics.
After a 150-mg injection of DMPA, the mean interval until return of ovulation is four to six months. Conception usually is delayed in former DMPA users when compared with women discontinuing oral contraceptives or IUDs. The median time to pregnancy following the last injection is nine to ten months, and studies have shown that almost 70 percent of former DMPA users conceive within the first twelve months following discontinuation, and over 90 percent conceive by twenty-four months, a rate comparable to that of oral contraceptive users. Nulliparous women (those who have never given birth to a child) and those using DMPA for many years experience the same return of fertility as other women studied.
Recent medical studies have addressed other safety issues regarding DMPA use. A large study conducted by the World Health Organization (WHO) showed that in aggregate, there is no overall increased risk of breast, cervical, or ovarian cancers in users of DMPA. DMPA users have a reduction in endometrial cancer for as long as ten years after discontinuation of the method. While there was evidence of a weak association between DMPA use and breast cancer in the subgroup of women under thirty-five who had used the drug within the previous four years, most experts feel that this represents a very weak promoter effect at a level similar to OC use. A single study showed a 7 percent reduction in bone density in premenopausal DMPA users compared to controls, but it is not clear whether this is a true biologic effect caused by low estrogen levels or due to selection bias.
Until more work is done in this area, some believe that it is prudent to screen potential DMPA users for osteoporosis risk factors and to provide additional counseling or evaluation for those with multiple risk factors.
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