Hormones 2016

Ethinylestradiol
Contains
Ethinylestradiol 10mcgs, 50mcgs, 1mg (BNF, 2016a). White uncoated
tablets, which also contain lactose, starch maize, magnesium stearate, IMS
99%, purified water (emc, 2016).
How it works
Oestrogens diffuse into their target cells and interact with a protein receptor.
Target cells include the female reproductive tract, the mammary gland, the
hypothalamus, and the pituitary. Oestrogens increase the hepatic synthesis
of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG),
and other serum proteins and suppress FSH from the anterior pituitary. This
cascade is initiated by initially binding to the oestrogen receptors (drugbank,
2013c).
Pharmacology
3-cyclopentylether of Ethinylestradiol. Ethinylestradiol, is chemically and
biologically identical to endogenous human estradiol (emc, 2016).
Absorption - Rapid and complete absorption follows oral intake of
ethinylestradiol (bioavailability 43%).
Metabolism - Hepatic. Quantitatively, the major metabolic pathway
for ethinylestradiol, both in rats and in humans, is aromatic
hydroxylation, as it is for the natural oestrogens.
Half life - 36 +/- 13 hours (drugbank, 2013c).
Indications
Oestrogen replacement therapy in females.
Pharmacokinetics
More potent than endogenous oestrogen because the liver cannot break it
down as quickly. Ethinylestradiol is rapidly and completely absorbed from
the gut but it undergoes some first pass metabolism in the gut wall.
Ethinylestradiol is rapidly distributed throughout most body tissues with
the largest concentration found in adipose tissue.More than 80% of
ethinylestradiol in serum is conjugated as the sulphate and almost all the
conjugated form is bound to albumin.
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Version 2016.3576– – Document LATEXed – 1st May 2016
[git] • Branch: 1.5 @ 26b5e6d • Release: 1.5 (2016-05-01)