The ORTHO-PREFEST regimen provides for a single oral tablet to be taken
once daily. The pink tablet containing 1.0 mg estradiol is taken on days
one through three of therapy; the white tablet containing 1.0 mg estradiol
and 0.09 mg norgestimate is taken on days four through six of therapy.
This pattern is then repeated continuously to produce the constant estrogen/intermittent
progestogen regimen of ORTHO-PREFEST.
The estrogenic component of ORTHO-PREFEST is 17b-estradiol.
It is a white, crystalline solid, chemically described as estra-1,3,5(10)-triene-3,17b-diol.
It has an empirical formula of C18H24O2
and molecular weight of 272.39.
The progestational component of ORTHO-PREFEST is micronized norgestimate,
a white powder which is chemically described as (17a)-17-(Acetyloxyl)-13-ethyl-18,19-dinorpregn-4-en-20-yn-3-one-3-oxime.
It has an empirical formula of C23H31NO3
and a molecular weight of 369.50.
Each tablet for oral administration contains 1.0 mg estradiol alone or
1.0 mg estradiol and 0.09 mg of norgestimate, and the following inactive
ingredients: croscarmellose sodium, microcrystalline cellulose, magnesium
stearate, ferric oxide red, and lactose monohydrate.