Birth Control Hormonal Methods (cont.)
Francisco Talavera, PharmD, PhD
Injections and Combination Injections
An injection of synthetic hormone medroxyprogesterone acetate (DMPA,
Depo-Provera) can be given every 3 months to stop ovulation. The injection is
given at a doctor's office. After injection, the medication is active within 24
hours and lasts for 3 months. It prevents the ovaries from releasing eggs.
- How effective: DMPA is an
extremely effective contraceptive option. Most other medications or a woman's
weight do not change its effectiveness. Within the first year of use, the
failure rate is 0.3%.
- Advantages: DMPA does not
produce the serious side effects that estrogen does, such as blood clotting. It
lowers the risk for certain endometrial and ovarian cancers. Irregular periods
may become regular.
- Disadvantages: Some women may
not have a period within the first year. Irregular bleeding can be treated by
giving the next dose earlier or by temporarily adding a low-dose estrogen.
Because DMPA lasts in the body for several months in women who have used it on a
long-term basis, it can delay the return to fertility. About 70% of former users
desiring pregnancy conceive within 12 months, and 90% of former users conceive
within 24 months. Other side effects, such as weight gain, depression, and
menstrual irregularities, may continue for as long as 1 year after the last
injection. Recent studies suggest a possible link between DMPA and bone density
loss. Results are conflicting and limited. This method does not protect against
One of the newest developments in contraception is a combined monthly
injection (medroxyprogesterone acetate [progesterone] and estradiol cypionate
[estrogen], brand name Lunelle). It recently received FDA approval in the United
States. The injections stop ovulation (like birth control pills do). They
thicken cervical mucus to prevent sperm from traveling up the Fallopian tubes to
fertilize an egg, and thin the uterine lining to prevent an egg from implanting.
Women who want to become pregnant may stop using Lunelle at any time. Some
women have an immediate return to fertility. Others may have to wait 60-90 days
for normal menstrual cycles.
- How effective: When used
correctly, Lunelle is 99.8% effective. One-year failure rates of less than
1% have been reported in clinical trials. In one US study of 782 women, no
pregnancies were reported after one year of use.
- Advantages:A woman can
regain fertility after 2-3 months after the last injection. Few users of
Lunelle experience problem periods or no periods. Lunelle can protect the
uterus from cancer and endometriosis and reduce the likelihood of ovarian
cysts and tumors.
- Disadvantages: Disadvantages
include irregular blood spotting, weight gain, headache, mild depression or
mood changes, and possible decrease in sexual desire. You are required to
see your health care provider each month for the injections and may have to
fill the prescription at the pharmacy and then take the medication with you
to the provider for the injection. Injections are given every 28-30 days and
no later than 33 days after the last injection. Timing is determined by the
number of days, not your menstrual period. Some women may not have a period
but should have the injection on schedule. In contrast to other hormonal
contraceptive methods, due to its novelty, associated cancer risk is not
known. More extensive worldwide use and additional studies may demonstrate
the risk, if any, on cancer of the reproductive tract. Some women may
experience changes in vision, especially for contact lens wearers. There is
a higher risk of gallbladder disease. Any woman with a history of blood
clots, stroke, heart disease, breast cancer, unexplained vaginal bleeding,
and high blood pressure should avoid Lunelle. Women older than 35 years who
smoke should not have these injections. This method does not protect against
Unfortunately, the combination injectable contraceptive is no longer
available in the United States, although it is popular in Central America and
South America and other parts of the world.
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