Depo Provera: An injectible contraceptive that is administered every three months. depo provera, depoprovera, injectable contraceptive, easy contraceptive, Depo Provera Contraceptive - An injectible contraceptive that is administered every three months. Depo Provera

Depo-Provera is a contraceptive or birth control product which is injected every 3 months.

It is the brand name for a depot formulation of medroxyprogesterone acetate manufactured by Pfizer Inc. It is a hormonal birth control method containing the pregnane (17α-hydroxyprogesterone derivative) progestin medroxyprogesterone acetate, without estrogen, and is administered to women in the form of an intramuscular injection once every 11 to 13 weeks. Depo-Provera causes the ovaries to stop releasing eggs.

Mechanism

The mechanism of action of progestin-only contraceptives depends on the progestin activity and dose. High dose progestin-only contraceptives, such as injectable Depo-Provera, completely inhibit follicular development and ovulation. Like all progestin-only contraceptives, Depo-Provera also increases cervical mucus viscosity, thereby inhibiting sperm penetration. In anovulatory cycles using progestin-only contraceptives, the endometrium is thin and atrophic. If the endometrium was also thin and atrophic during an ovulatory cycle, this could theoretically interfere with implantation of a blastocyst (embryo).

Failure Rates

Most sources cite the failure rate for Depo-Provera at 0.3 percent annually, which would be three women out of a thousand per year. This number is based on large prospective clinical trials of women actually using Depo-Provera. Another method of determining efficacy is based on retrospective surveys that rely on a woman's recall of her contraceptive use over the past 4 to 5 years, such as the National Surveys of Family Growth (NSFG) -- a primary source of data used for estimating user-dependent contraceptive failure rates in the United States. The number of women in the NSFG retrospective survey using Depo-Provera, Norplant, and IUDs is small, much smaller then number of women in the prospective clinical trials that evaluated the effectiveness of Depo-Provera, Norplant, and IUDs. NSFG survey data may uncover more realistic failure rates for user-dependent contraceptive methods, but has been found to produce unrealistically high failure rates for contraceptive methods that are not user-dependent (this has been attributed to contraceptive overreporting). For example, NSFG survey data combined from 1988 and 1995 for Depo-Provera, Norplant, and IUDs produced a combined standardized failure rate for these three methods of 3.2 per year. Higher rates (combining Depo-Provera, Norplant, and IUD use) for women aged 20-24 (5.1 percent) and for cohabiting couples (6.5 percent). The two year combined failure rate for Depo-Provera, Norplant, and IUD use for women aged 20-24 was 10.9 percent, which comes out to one woman in ten.

Benefits

Depo-Provera has several advantages:

Pregnancy and breastfeeding

Depo Provera may be used by breast-feeding mothers. Heavy bleeding is possible if given in the immediate postpartum time and is best delayed until six weeks after birth. It may be used within five days if not breast feeding. While a study showed "no significant difference in birth weights or incidence of birth defects" and "no significant alternation of immunity to infectious disease caused by breast milk containing DMPA", a subgroup of babies whose mothers started Depo Provera at 2 days postpartum had a 75% higher incidence of doctor visits for infectious diseases during their first year of life.

A larger study with longer follow-up concluded that "use of DMPA during pregnancy or breastfeeding does not adversely affect the long-term growth and development of children". This study also noted that "children with DMPA exposure during pregnancy and lactation had an increased risk of suboptimal growth in height," but that "after adjustment for socioeconomic factors by multiple logistic regression, there was no increased risk of impaired growth among the DMPA-exposed children." The study also noted that effects of DMPA exposure on puberty require further study, as so few children over the age of 10 were observed.

Disadvantages and side effects

Warnings and precautions

Black box warning

While it has long been known that Depo-Provera causes bone loss, it has recently been discovered that the osteoporotic effects of the injection grow worse the longer Depo-Provera is administered, may remain long after the injections are stopped, and may be irreversible. For this reason, on November 17, 2004 the United States Food and Drug Administration and Pfizer agreed to put a "black box warning" on Depo-Provera's label. However, the World Health Organization (WHO) advises that the use of Depo Provera should not be restricted.

It is unclear whether the bone density loss associated with Depo-Provera use is reversible, and if so, how completely. Three studies have suggested that bone loss is reversible after the discontinuation of Depo-Provera, although one notes that bone loss was not reversible in long-term users of Depo-Provera. Other studies have suggested that the effect of Depo-Provera use on post-menopausal bone density is minimal, perhaps because Depo users experience less bone loss at menopause. However, as of 2006, no study has directly examined fracture risk in post-menopausal women who have used Depo-Provera; therefore, the risk is unknown. Pfizer and the FDA recommend that Depo-Provera not be used for longer than 2 years, unless there is no viable alternative method of contraception, due to concerns over bone loss.

Side effects

Depo-Provera may have side effects, in order of greatest frequency: menstrual irregularities (irregular bleeding, amenorrhoea absence of bleeding or metrorrhagia constant bleeding) nausea, vomiting, headaches, dizziness, breast swelling and tenderness, depression, skin disorders (rash, hot flushes, acne, alteration hair growth), alteration in appetite, altered weight and changes in libido. Other possible associated side effects are set out in the product licensing and patient labelling with some rare but potentially serious effects being: convulsions, jaundice, urinary tract infections, allergic reactions, fainting, paralysis, osteoporosis, lack of return to fertility, deep vein thrombosis and pulmonary embolus.

Related studies

Contraindications

The WHO Medical Eligibility Criteria for Contraceptive Use and RCOG Faculty of Family Planning & Reproductive Health Care (FFPRHC) UK Medical Eligibility Criteria for Contraceptive Use list the following as conditions where use of Depo-Provera is not usually recommended or should not be used because of an unacceptable health risk or because it is not indicated:

Conditions where the theoretical or proven risks usually outweigh the advantages of using Depo-Provera:

Conditions which represent an unacceptable health risk if Depo-Provera is used:

Conditions where use of Depo-Provera is not indicated and should not be initiated:

Other uses

Depo-Provera is also used with male sex offenders as a form of chemical castration as it has the effect of drastically reducing sex drive in males.

Controversy over Approval of Depo-Provera in the United States

There was a long, controversial history regarding the approval of Depo-Provera by the U.S. Food and Drug Administration. The original manufacturer, Upjohn, applied repeatedly for approval. FDA advisory committees unanimously recommended approval in 1973, 1975 and 1992, as did the FDA's professional medical staff, but the FDA repeatedly denied approval. Ultimately, on October 29, 1992, the FDA approved Depo Provera, which had by then been used by over 30 million women since 1969 and was approved and being used by nearly 9 million women in more than 90 countries, including the United Kingdom, France, Germany, Sweden, Thailand, New Zealand and Indonesia. Points in the controversy included:

Aftermath