Home » Drug Information » FDA Approved Drugs » 1996
Medical Areas: Endocrinology | Obstetrics/Gynecology (Women’s Health)
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Estrostep (norethindrone acetate and ethinyl estradiol)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Approval Status: Approved October 1996
Treatment Area: oral contraceptive
Estrostep, a graduated Estrophasic oral contraceptive, has been
approved as an oral contraceptive. Other birth control pills
usually contain a constant dose of estrogen and progestin, or
change the dose of progestin throughout the cycle. Estrostep is the
only oral contraceptive to combine low, gradually increasing
amounts of estrogen (20, 30, 35 mcg ethinyl estradiol) with a low,
constant dose of progestin (one mg norethindrone acetate). When
used as directed, Estrostep is greater that 99% effective in
preventing pregnancy, as are all other combination OC's.
Early generation pills contained doses of estrogen as high as
150 mcg. Studies linking high doses of the hormone to adverse
effects have resulted in a progressive reduction of estrogen
content, leading to today's low-dose pills. The most common
pill prescribed today contains a constant 35-mcg-estrogen dose.
With Estrostep, graduated amounts of estrogen are introduced
into the woman's body in three phased-in doses during each
menstrual cycle: 20 mcg of estrogen for the first five days, 30 mcg
for the next seven days, and 35 mcg for the last nine days, for a
total of 21 days. Estrogen and progestin are stopped for the
remaining seven days of the cycle, resulting in a woman's
monthly menstrual period. The 28-day pill pack will contain seven
inactive tablets to help women maintain their regimen.
While both estrogen and progestin play a role in the efficacy of
combination OC's, the estrogen component also contributes to
maintaining menstrual cycle control. Clinical studies of Estrostep
show that its unique graduated low estrogen doses are sufficient to
provide good endometrial support. Few women in these studies
discontinued Estrostep due to missed periods and breakthrough
bleeding. These particular complaints are frequent among women who
are trying the pill for the first time.
In a comparative clinical study involving more than 1,200 women
(769 receiving Estrostep), Estrostep was shown to have a high
degree of patient acceptance, with a side effect profile comparable
to other low-dose OC's.
OC's are associated with side effects. Nausea, vomiting, and
breakthrough bleeding are common side effects that may subside
within the first three months of use. Clinical studies with
Estrostep showed that weight gain and nausea each caused less than
one percent of women to withdraw from therapy.