Contraception - Doses and medication

Some clinicians still informally prescribe combinations
of available birth control pills “off label” particularly
if women have a medication already on
hand. In 1997, the US Food and Drug Administration
(FDA) recognized that seven OCPs available at that
time could be safely and effectively used as EC.20
These included the medications listed in Table 7.5.
The drawback is that they require taking a relatively
large number of tablets at one time.
Only Plan B is currently marketed specifically for
EC in the USA. Although it can be started within
120 hours of unprotected intercourse, it is most successful
if used immediately. There have been virtually
no contraindications. Emergency oral contraception
is of such short duration and utilizes such a low
hormonal dose that it is not thought to pose a risk
for women at risk of stroke, deep vein thrombosis, or
cardiovascular disease, even those who are not usually
considered candidates for combination oral contraceptives.
For almost all of these women, their risk
from an unintended pregnancy is far greater than
their risk from the medication. Plan B, the progestinonly
OCPs, or the IUD is recommended for women
who absolutely must avoid estrogen completely. Some
changes in the following menstrual cycle (amount,
duration, timing) can be anticipated in about 7% of
women.
Preven, an EC previously available in the USA
consisted of four tablets, each composed of 0.25 mg
of levonorgestrel and 0.05 mg of ethinylestradiol. It is
no longer marketed in the USA. Its dose is mimicked
by many of the OCPS listed in Table 7.5.
Plan B, which became available in 1999, consists of
two tablets of levonorgestrel, 0.75 mg. According to the
product labeling, one tablet is taken initially and the
second tablet is taken in 12 hours; both tablets should be
taken within 72 hours of unprotected intercourse.
While research data indicate both tablets may be taken
initially at one time within 120 hours of unprotected
intercourse with no change in efficacy,21 it is more
successful when initiated closer in time to the episode
of unprotected intercourse. Neither a pelvic examination
nor a pregnancy test is necessary before use. The
mechanism of action appears to influence fertilization.
Another form of emergency contraception is the
copper IUD; since an actual visit to a clinician is
required for placement it is not as “convenient” as
oral methods. Its “window” of efficacy is longer as it
can be inserted within five days of unprotected intercourse.
Copper IUDs are over 99% efficacious and
have the additional advantage of providing continuing
contraception for the woman who desires it.
Mifepristone (RU 486) is approved by the FDA
for medical pregnancy termination, but not EC. It has
been used at a lower dose as EC in China. It prevents
85% of the pregnancies expected to occur without
treatment and can be given up to 120 hours after
unprotected intercourse. The only side effect is
delayed onset of the next menses. Dosages of 600 mg,
50 mg and 7 mg have been similarly efficacious. The
smallest dose is associated with the lowest incidence
of side effects.11,22
Providers may consider counseling women about
EC and encouraging them to have a method “on
hand.” Women who do not use regular contraception,
women who have a history of a past unintended
pregnancy, and those who use contraceptive methods
with a high rate of method failure may find EC
particularly beneficial.
Women who use EC should be given additional
opportunities to consider whether a more permanent
or better method of contraception is warranted.
An excellent resource is the Emergency Contraception
website accessible at http://ec.princeton.edu/
questions/index.html which has information for a lay
audience and health professionals. It also lists options
for access by zip code.

Posted in: Contraception,Health