Santa, where did you get the idea nolvadex and estrogen have a very similar structure?
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Novadex
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Estrogen
Not the slightest bit alike
Internet and various medical journals. You can google nolvadex similar to estrogen and you'll gets lots of results.
Nolva does break down into various other things, if for example looking at 4-Hydroxytamoxifen or N-Desmethyltamoxifen, it looks similar. And then we have several more to look at.
We also have about 12 metabolic pathways for estradiol with different chemical structures so linking that one picture isn't really fair either.
For example:
The crystallographic structure of 4-hydroxytamoxifen interacts with the amino acids of the ER within the ligand-binding domain. The contact between the phenolic group, water molecule, and glutamate and arginine in the receptor (Glu 353/Arg 394) resolves in high affinity binding
so that 4-hydroxy tamoxifen, with a phenolic ring that resembles the A ring of 17b-estradiol, has more than 100 times higher relative binding affinity than tamoxifen, which has no phenol. If its OH group is eliminated or its position is changed the binding affinity is reduced.
Or from another site:
Estradiol and tamoxifen. Estradiol, shown at the top, is a small carbon-rich steroid.
Tamoxifen, shown at bottom, mimics the shape and chemical composition of estradiol. Tamoxifen, however, has an extra chain attached in the middle that is important for its antagonistic action.
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From a third site about long the term use, this should be noted from just regular use of nolvadex, when you also use it longterm and/or in very high doses, my understanding is that you can get high estrogen side effects:
Although classed as an estrogen antagonist it should be noted that in some parts of the body tamoxifen actually acts as an estrogen agonist meaning it actually acts in an estrogenic manner as opposed to how most think of it being which is an anti-estrogen. When it acts in an estrogenic fashion in the liver for instance, tamoxifen can increase levels of sex hormone binding globulin (SHGB) which acts to bind to testosterone thus lowering free testosterone in the body. Another negative of tamoxifen action in the liver is its ability to suppress production of the peptide hormone IGF-1.
Granted, I might have misinterpreted the information i've read and i'd be happy for you to enlighten me, but otherwise I'm curious why you think my statement was wrong.
I did this research for using nolvadex during cycle as an preemptive countermeasure to gyno but decided against it.