a. Depo-medroxy progesterone acetate (Depo-Provera) is the most commonly used injectable progestin in the world. It was finally approved for use in the United States in 1992. It is excellent for use in women who breast-feed or for short-term use where estrogen is contraindicated.
b. Composition and mode of action.
(1) Depo-medroxy progesterone acetate is given by deep intramuscular injections. A dosage of 150 mg must be given every
(2) Its action is to shut down the LH surge and suppress LH and FSH levels. It also causes an atrophic endometrium and thick impenetrable cervical mucus. Depo-Provera is so effective that long-time users may be as much as 2 weeks late for their next injections.
c. Efficacy: Only 0.3% of women will experience accidental pregnancy within the first year of use. Giving 400 mg of Depo-Provera in the more concentrated form every 6 months decreases the effectiveness rate throughout the 6-month period.
d. Indications: Women who may not use estrogen, women who breastfeed, older women, women who need short-term but effective contraception may use Depo-Provera.
(1) Risk of endometrial and ovarian cancer and PID is decreased.
(2) There is less menstrual blood loss, and therefore anemia is decreased.
(3) A decrease in dysmenorrhea and mittelschmerz is seen.
(4) Depo-Provera is a reversible form of birth control, although the return of fertility is slower than it is for other types of hormonal contraception.
(5) Risk of ectopic pregnancies decreases to 1.3/1000 women-years as compared with 6.5/1000 women-years in women who use no contraception.
(6) Amenorrhea is of advantage in certain women because as many as 80% of women are amenorrheic after 3 years of use.
(7) Use with antibiotics is safe. The only drug known to decrease the effectiveness of Depo-Provera is cytodren. Because it is given parenterally, it is not dependent on the gastrointestinal tract. Improvement of seizure disorder results from the sedating effects of progestins.
f. Side effects.
(1) The menstrual cycle changes (increased days of light bleeding but not increased blood loss).
(2) Amenorrhea develops with time.
(3) Weight gain: The patient may gain up to 14 pounds with 4 years of use.
(4) Breast tenderness may occur.
(5) Depression may occur.
(6) Bone density decreases, which is reversible after discontinuation.
(7) The return of fertility is delayed for 6 months to 1 year after ] discontinuing use.