Estrogen and Androgen
Estrogen and Androgen
Estrogen and Androgen
Cadungog
ESTROGENS &
ANDROGENS
PART 1
Overview
Estrogens and androgens are sex hormones produced by the
gonads. These hormones are necessary for conception,
embryonic maturation, and development of primary and
secondary sexual characteristics at puberty. The sex
hormones are used therapeutically for contraception,
management of menopausal symptoms, and replacement
therapy in hormone deficiency. Several antagonists are
effective in the treatment or prevention of hormone-
responsive cancers. Sex hormones are synthesized from the
precursor, cholesterol, in a series of steps that includes
shortening of the hydrocarbon side chain and hydroxylation of
the steroid nucleus. Aromatization is the last step in
estrogen synthesis.
Estrogens
Postmenopausal HT
The primary indication for estrogen therapy in
postmenopausal women is menopausal symptoms, such
as vasomotor instability and vaginal atrophy. A common
oral preparation used for the treatment of menopausal
symptoms is conjugated equine estrogens.
Benefits associated with
postmenopausal estrogen
replacement.
NUMBER 2
Contraception
The combination of an estrogen and progestogen
provides effective contraception via the oral,
transdermal, or
vaginal route.
NUMBER 3
Other Uses
Estrogen therapy mimicking the natural cyclic pattern, and
usually in combination with a progestogen, is instituted
to stimulate development of secondary sex
characteristics in young women with primary
hypogonadism. Similarly,
replacement therapy is used for women who have
hormonal deficiencies due to surgical menopause or
premature
ovarian failure.
PHARMACOKINETICS
Naturally Occurring Estrogens
These agents and their esterified or conjugated
derivatives are readily absorbed through the
gastrointestinal tract,
skin, and mucous membranes. Taken orally, estradiol is
rapidly metabolized (and partially inactivated) by the
microsomal enzymes of the liver. Micronized estradiol
has better bioavailability. Although estradiol is subject
to
first-pass metabolism, it is still effective when taken
orally.
Synthetic Estrogens
These compounds, such as ethinyl estradiol and estradiol
valerate are well absorbed after oral administration.
Estradiol valerate is a prodrug of estradiol which is
rapidly cleaved to estradiol and valeric acid. The
synthetic
estrogens are fat soluble, stored in adipose tissue, and
slowly released. These compounds have a prolonged
action
and a higher potency compared to the natural estrogens.
Metabolism