Depot Medroxyprogesterone Acetate (DMPA) Contraceptive - Uses, Side Effects and Dosage

Depot medroxyprogesterone acetate also referred to as DMPA or Medroxyprogesterone is a long acting progestin-only reversible hormonal contraceptive birth control drug which is injected every 3 months in order to maintain its effectiveness. It is an aqueous suspension for depot injection of the pregnane 17a-hydroxyprogesterone-derivative progestin medroxyprogesterone acetate.
It is approved internationally for contraceptive use as well as for management of endometriosis-related pain.

DMPA Contraceptive (Medroxyprogesterone) - Mechanism Of Action

The mechanism of action of progestogen-only contraceptives like DMPA depends on the progestogen activity and dose. High-dose progestogen-only contraceptives, such as injectable DMPA, inhibit follicular development and prevent ovulation as their primary mechanism of action.
The progestogen decreases the pulse frequency of gonadotropin-releasing hormone (GnRH) release by the hypothalamus, which decreases the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the anterior pituitary. Decreased levels of FSH inhibit follicular development, preventing an increase in estradiol levels. Progestogen negative feedback and the lack of estrogen positive feedback on LH release prevent a LH surge. Inhibition of follicular development and the absence of a LH surge prevent ovulation.
A secondary mechanism of action of all progestogen-containing contraceptives is inhibition of sperm penetration by changes in the cervical mucus. Inhibition of ovarian function during DMPA use causes the endometrium to become thin and atrophic. Theoretically, these changes in the endometrium could prevent implantation. However, because DMPA is highly effective in inhibiting ovulation and sperm penetration, the possibility of fertilization is negligible.

Effectiveness of Medroxyprogesterone (DMPA)

The life-table first-year failure rates for 8,183 women using Depo-Provera in seven prospective clinical trials were: 0%, 0%, 0.1%, 0.2%, 0.2%, 0.3%, and 0.7%, with a weighted average of 0.3%.
The Pearl Index first-year failure rates for 2,042 women using depo-subQ 104 in three prospective clinical trials were: 0%, 0%, and 0%, with a weighted average of 0%. Trussell's estimated perfect use first-year failure rate for Depo-Provera is the weighted average of failure rates in seven clinical trials: 0.3%.

Availability And Packaging

Depot medroxyprogesterone acetate also referred to as DMPA or Medroxyprogesterone is available in the form of Depo-Provera Contraceptive Injection which is a 150 mg aqueous suspension of medroxyprogesterone acetate for intramuscular injection. The Depo-Provera injection is required 4 times a year (once every 13 weeks) to maintain high effectiveness rate.
It is also available as depo-subQ provera 104 which is a 104 mg aqueous suspension of medroxyprogesterone acetate. It contains 69 percent of the hormone found in the original Depo Provera shot. It is applied in the form of a subcutaneous injection, which may cause less pain. Depo-subQ provera medicine must be injected into the thigh or abdomen four times a year to maintain effectiveness.

DMPA (Depo-Provera) Contraceptive Injection – Dosage

DEPO-PROVERA Contraceptive Injection is given as an intramuscular injection (a shot) in the buttock or upper arm once every 3 months (13 weeks). At the end of the 3-month interval, you will need to go to your doctor for your next injection in order to continue your contraceptive protection.
Even though the contraceptive effects of DMPA take time to wear off, there is still a possibility of becoming pregnant if you miss your scheduled shot of Depo Provera.

DMPA Contraindications

The Conditions where the theoretical or proven risks usually outweigh the advantages of using DMPA like Depo-Provera because of an unacceptable health risk or because it is not indicated are listed below. This list had been originally prepared by WHO Medical Eligibility Criteria for Contraceptive Use and RCOG Faculty of Family Planning & Reproductive Health Care (FFPRHC) UK
* Multiple risk factors for arterial cardiovascular disease
* Current deep vein thrombosis (DVT) or pulmonary embolus (PE)
* Migraine headache with aura while using Depo-Provera
* Before evaluation of unexplained vaginal bleeding suspected of being a serious condition
* Past history of breast cancer and no evidence of current disease for 5 years
* Active liver disease: (acute viral hepatitis, severe decompensated cirrhosis, benign or malignant liver tumours)
* Conditions of concern for hypo-estrogenic effects and reduced HDL levels theoretically increasing cardiovascular risk like Hypertension with vascular disease, Current and history of ischemic heart disease, History of stroke, Diabetes for over 20 years or with nephropathy/retinopathy/neuropathy or vascular disease
Conditions which represent an unacceptable health risk if Depo-Provera is used
Current or recent breast cancer (a hormonally sensitive tumour)
Conditions where use of Depo-Provera is not indicated and should not be initiated:
* Pregnancy

Advantages of Medroxyprogesterone (Depo-Provera):

* Highly effective at preventing pregnancy.
* Injected every 12 weeks. The only continuing action is to book subsequent follow-up injections every twelve weeks, and to monitor side effects to ensure that they do not require medical attention.
* No estrogen. No increased risk of deep vein thrombosis (DVT), pulmonary embolism (PE), stroke, or myocardial infarction.
* Minimal drug interactions (compared to other hormonal contraceptives).
* Decreased risk of endometrial cancer. Depo-Provera reduces the risk of endometrial cancer by 80%. The reduced risk of endometrial cancer in Depo-Provera users is thought to be due to both the direct anti-proliferative effect of progestogen on the endometrium and the indirect reduction of estrogen levels by suppression of ovarian follicular development.
* Decreased risk of iron deficiency anemia, pelvic inflammatory disease (PID), ectopic pregnancy, and uterine fibroids.
* Decreased symptoms of endometriosis.
* Decreased incidence of primary dysmenorrhea, ovulation pain, and functional ovarian cysts. * Decreased incidence of seizures in women with epilepsy. Additionally, unlike most other hormonal contraceptives, Depo-Provera's contraceptive effectiveness is not affected by enzyme-inducing antiepileptic drugs.
* Decreased incidence and severity of sickle cell crises in women with sickle-cell disease.

Medroxyprogesterone (DMPA, Depo-Provera) Side Effects, Warnings and Precautions

* Takes three weeks to take effect if given after the first five days of the period cycle. Effective immediately if given during the first five days of the period cycle.
* Offers no protection against Sexually transmitted diseases (STDs).
* Depo-Provera can affect menstrual bleeding. After a year of use, 55% of women experience amenorrhoea; after 2 years, the rate rises to 68%. In the first months of use irregular or unpredictable bleeding or spotting, or rarely, heavy or continuous bleeding was reported.
* Delayed return of fertility after stopping use. The average return to fertility is 9 to 10 months after the last injection. By 18 months after the last injection, fertility is the same as that in former users of other contraceptive methods.
* Long-term studies of users of Depo-Provera have found slight or no increased overall risk of breast cancer. However, the study population did show a slightly increased risk of breast cancer in recent users under age 35, similar to that seen with the use of combined oral contraceptive pills.
* A study of accidental pregnancies among poor women in Thailand found that infants who had been exposed to Depo-Provera during pregnancy had a higher risk of low birth weight and an 80% greater-than-usual chance of dying in the first year of life.
*It has recently been discovered that the osteoporotic effects of the injection grow worse the longer Depo-Provera is administered. Pfizer and the FDA recommend that Depo-Provera not be used for longer than 2 years due to concerns over bone loss.
In the largest clinical trial of Depo-Provera, the most frequently reported adverse reactions were: menstrual irregularities which include bleeding or amenorrhea or both , abdominal pain or discomfort, weight changes, headache, asthenia (weakness or fatigue), and nervousness.

Further Information

Manufacturers pamphlet: Pfizer - Depo Provera



Considerable portions of the text here is from http://en.wikipedia.org/wiki/Depo-Provera and is reproduced here under the Creative Commons Attribution-ShareAlike License