Home » Drug Information » FDA Approved Drugs » 1997
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 March 1997
Treatment Area: oral contraception
Estrostep, the first oral contraceptive (OC) in the a new class
called Estrophasic has been approved. The Estrophasic OC phases in
gradually increasing doses over the woman’s cycle. Estrophasic is
the first new class of Ocs to be marketed in more than 10 years.
Estrostep works by providing low, gradually increasing amounts of
estrogen (20, 30, 35 mcg ethinyl estradiol) with a low, constant
dose of progestin (one mg norethindrone acetate).
Monophasic birth control pills contain a constant doe of
estrogen and progestin. Triphasics change the dose of progestin
throughout the cycle while keeping the estrogen dose constant or
increasing then decreasing the estrogen dose. This is the first OC
that gradually phases in the estrogen component of the pill in
increasing doses. With Estrostep, low doses of estrogen are phased
into the woman’s body in three graduated steps during the menstrual
cycle: 20 micrograms (mcg) of estrogen (ethinyl estradiol) 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.
When used as directed, Estrostep is greater than 99% effective
in preventing pregnancy , as are all other combination Ocs.
Estrostep was found to be well-tolerated in a clinical study
involving 1,200 patients (769 receiving Estrostep), with a low
overall drop-out rate due to side effects.
In addition to contraception, Estrostep, like all oral
contraceptives, may also provide several health benefits including:
lower incidence of ovarian cysts, lower incidence of pelvic
inflammatory disease, reduced likelihood of developing cancer of
the ovaries and cancer of the lining of the uterus, more regular
periods, lighter menstrual flow and less menstrual discomfort.
However, all Ocs are also associated with certain side effects.
Nausea/vomiting, breakthrough bleeding and headaches are common.
Clinical studies with Estrostep showed that these side effects as
well as weight gain each caused fewer than one percent of women to
withdraw from therapy.
The most common pill prescribed today contains a constant 35 mcg
estrogen dose. 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.
Oral contraceptives are not appropriate for all patients. The
use of oral contraceptives is associated with some serious adverse
side effects as well, such as increased risk of myocardial
infarction, thromboembolism, stroke, hepatic neoplasia, and
gallbladder disease. The risk of serious morbidity and mortality is
very small in healthy women without underlying risk factors. It is
important to note that oral contraceptives do not protect against
HIV infection (AIDS) and other sexually transmitted diseases. Women
who use oral contraceptives should be strongly advised not to
smoke. Women should discuss the benefits and risks of Ocs with
their healthcare provider.