General
Description & Use
Natural Oestrogen/ Estrogen. A female hormone used for the treatment
of the oestrogen deficiency syndrome. Also popular for M2F
transsexuals in gender reassignment.
List
of estradiol medications
The following are marketed versions of estradiol:
Oral
versions: Estrace, Activella (also contains a progestin), estradiol
acetate, Progynova,
Estrofem®, Zumenon
Transdermal preparation: Alora, Climara,
Vivelle, Vivelle-Dot, Menostar, Estraderm
TTS
Ointments: Estrasorb Topical, Estrogel, Elestrin
Injection: Estradiol cyprionate: Lunelle monthly injection, Estradiol
valerate
Vaginal ointment: Estrace Vaginal Cream, Premarin
Cream
Vaginal ring: Estring (estradiol acetate), Femring
Estradiol is also part of conjugated
estrogen preparations, including Premarin but is
not the major ingredient (Premarin consists of hundreds of estrogen
derivatives due to its natural source...pregnant mare urine.
Estradiol
(17ß-estradiol) (also oestradiol) is a sex hormone. Mislabelled
the "female" hormone, it is also present in males; it
represents the major estrogen in humans. Estradiol has not only
a critical impact on reproductive and sexual functioning, but
also affects other organs including bone structure. During the
reproductive years, most estradiol in women is produced by the
granulosa cells of the ovaries by the aromatization of androstenedione
(produced in the theca folliculi cells) to estrone, followed by
conversion of estrone to estradiol by 17ß-hydroxysteroid
reductase. Smaller amounts of estradiol are also produced by the
adrenal cortex, and (in men), by the testes. Estradiol
is not only produced in the gonads: in both sexes, precursor hormones,
specifically testosterone, are converted by aromatization to estradiol.
In particular, fat cells are active to convert precursors to estradiol,
and will continue to do so even after menopause. Estradiol is
also produced in the brain and in arterial walls.
Estrofem®
was especially developed and indicated for the treatment of oestrogen
deficiency symptoms in women without a uterus, with effective
symptom relief and good tolerability (continuous therapy with
calendar pack of 28 tablets containing 1mg 17b-oestradiol). As
there is no increased risk of developing cancer of the uterus
lining in women without a uterus, they need not to take an additional
progestogen. The drug is available in different dosages because
a standardised unique dose is not optimal for every woman. Studies
have demonstrated that after four weeks of treatment there is
a significant reduction in hot flushes and other menopausal complaints.
The administration of Estrofem® results in a significant increase
of bone density.
Female
reproduction
In the female, estradiol acts as a growth hormone for tissue of
the reproductive organs, supporting the lining of the vagina,
the cervical glands, the endometrium and the lining of the fallopian
tubes. It enhances growth of the myometrium. Estradiol appears
necessary to maintain oocytes in the ovary. During the menstrual
cycle, estradiol that is produced by the growing follicle triggers,
via a positive feedback system, the hypothalamic-pituitary events
that lead to the luteinizing hormone surge, inducing ovulation.
In the luteal phase estradiol, in conjunction with progesterone,
prepares the endometrium for implantation. During pregnancy estradiol
increases due to placental production.
Sexual development
The development of secondary sex characteristics in women is driven
by estrogens, specifically estradiol. These changes are initiated
at the time of puberty, most enhanced during the reproductive
years, and become less pronounced with declining estradiol support
after the menopause. Thus, estradiol enhances breast development,
and is responsible for changes in the body shape affecting bones,
joints, fat deposition. Fat structure and skin composition are
modified by estradiol.
Bone
There is ample evidence that estradiol has a profound effect on
bone. Individuals without estradiol (or other estrogens) will
become tall and eunuchoid as epiphysieal closure is delayed or
may not take place. Bone structure is affected resulting in early
osteopenia and osteoporosis. Also, women past menopause experience
an accelerated loss of bone mass due to a relative estrogen deficiency.
Estradiol
medication
Estrogen is marketed in a number of ways to address issues of
hypoestrogenism. Thus there are oral, transdermal, topical, injectable,
and vaginal preparations. Furthermore, the estradiol molecule
may be linked to an alkyl group at C3 position to facilitate the
administration. Such modifications give rise to estradiol acetate
(oral and vaginal applications) and to estradiol cyprionate (injectable).
Oral
preparations are not necessarily predictably absorbed and subject
to a first pass through the liver where they can be metabolized
and also initiate unwanted side effects. Thus, alternative routes
of administration have been developed that bypass the liver before
primary target organs are hit. Transdermal and transvaginal routes
are not subject to the initial liver passage.
A
more profound alteration is ethinylestradiol,
the most common estrogen ingredient in combined oral contraceptive
pills and available here at NPD in pure form.
Hormone replacement therapy (HRT)
If severe side effects of low levels of estradiol in a woman's
blood are experienced (commonly at the beginning of menopause
or after oophorectomy), hormone replacement therapy may be prescribed.
Often such therapy is combined with a progestin.
Estrogen
therapy may be used in treatment of infertility in women when
there is a need to develop sperm-friendly cervical mucus or an
appropriate uterine lining. Estrogen therapy is also used to maintain
female hormone levels in male-to-female
transsexuals. Also see
a list of all hormones available from NPD here.
