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Estrostep 21

(norethindrone acetate and ethinyl estradiol) Tablets, USP

(Each white triangular tablet contains 1 mg norethindrone acetate and 20 mcg ethinyl estradiol; each white square tablet contains 1 mg norethindrone acetate and 30 mcg ethinyl estradiol; each white round tablet contains 1 mg norethindrone acetate and 35 mcg ethinyl estradiol.)

Patients should be counseled that this product does not protect against HIV infection (AIDS) and other sexually transmitted diseases.


ESTROSTEP is a graduated estrophasic providing estrogen in a graduated sequence over a 21-day period with a constant dose of progestogen.

ESTROSTEP 21 provides for a 21-day dosage regimen of oral contraceptive tablets.

Each white triangle-shaped tablet contains 1 mg norethindrone acetate [(17 alpha)- 17-(acetyloxy)-19-norpregna-4-en-20-yn-3-one] and 20 mcg ethinyl estradiol [(17 alpha)- 19-norpregna-1,3,5(10)-trien-20-yne-3,17-diol]; each white square-shaped tablet contains 1 mg norethindrone acetate and 30 mcg ethinyl estradiol; and each white round tablet contains 1 mg norethindrone acetate, 35 mcg ethinyl estradiol. Each tablet also contains calcium stearate; lactose; microcrystalline cellulose; and starch.

The structural formulas are as follows:

ESTROSTEP (Norethindrone Acetate and Ethinyl Estradiol) structural formula illustration

Each ESTROSTEP 21 tablet dispenser contains five white triangular tablets, seven white square tablets, and nine white round tablets. These tablets are to be taken in the following order: one triangular tablet each day for five days, followed by one square tablet each day for seven days, and then one round tablet each day for nine days.

Last reviewed on RxList: 4/23/2008
This monograph has been modified to include the generic and brand name in many instances.


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