I had this info a long time but could not find it it is a must read if your on this or thinking of using it. Here is a cut and paste I would give a link but I don't think it's aloud.
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Ahhhhh-romasin®! The king of anti-estrogens.

This post is kind of long, but take the time to read it, it's probably the most important thing you'll ever read if you're a BB'er (haha well maybe not, but there's some gold in here)

Exemestane, sold under the name Aromasin® by Pfizer, is an orally available suicidal aromatase inhibitor. <This sentence describes exactly why exemestane is the king of Anti-E's for bodybuilding purposes.

Because exemestane is steroidal this gives it a favorable estrogen suppression profile and confers a few really awesome benefits over other anti-estrogens both on paper and in real experience. Steroidal anti-estrogens have the benefit of being lipid-friendly and they all lower SHBG which increases the ratio of free to bound testosterone, which as many experienced BB'ers know can have a relatively profound positive impact on gains.

I think it is important to understand how drugs work in order to properly dose them, exemestane is a suicidal aromatase inhibitor, this means that it binds with aromatase enzymes and as it does so permanently disables the enzyme and destroys it. Hence the "suicidal" this chemical is like a kamikaze pilot out to destroy your aromatase enzymes which is what makes it so special.

Exemestane's half life in the male body is actually very short (~9 hours) and it is quickly eliminated, however, since as soon as it enters your bloodstream it quickly destroys 80-90% of the aromatase enzymes present in your body, it is effective in maintaining significant reductions in estrogen for up to 72 hours after a single 25mg dose. Estrogen levels only begin to rise again after your body has begun to make new aromatase enzymes to replace the ones destro by exemestane.

There is a great study on the pharmacokinetics of exemestane in men which found the following:
-24 hours after one 25mg dose estrogen levels are reduced by 70-80%
-72 hours later estrogen levels are still 40% below baseline even though the drug itself is almost completely eliminated
-120 hours after initial dose estrogen levels return to baseline (without rebounding)

this means that you can find the timing and dosage that works for you, i've seen some guys recommend between 25mg ED and 12.5mg e4d, and you can see why both are effective while providing different levels of estrogen suppression, and it is this flexibility that makes exemestane such a versatile Anti-E.

BUT WAIT, there's more. Aromasin is also a badass PCT drug! In males exemestane was found to increase total testosterone by ~60% after 10 days @ 25mg/day, however the same study found that while it increased total testosterone by 60% free testosterone was increased by over 100 percent! that's right, it DOUBLES bio-available testosterone (natty of course).

I can tell you this much, when I take aromasin for PCT the results are dramatic, honestly my Libido is never absent at any point during PCT and I absolutely feel great within a matter of days, and this is taking 12.5mg ED, the only side effect i notice is stiff joints and other stiff areas

the good:
-powerful aromatase inhibitor capable of stopping gynecomastia completely on its own (for aromatizing compounds)
-has powerful bloat-reduction effects
-lowers SHBG, increasing free test & makes all other anabolic steroids more bio-available (read: more gains)
-can actually boost Libido on and off cycle
-increases IGF-1
-NO adverse changes in lipid profiles for men (granted if you are using it on cycle this may be different)
-is NOT liver toxic
-no estrogen rebound

the bad:
-typical aromatase inhibitor issues here include stiff joints and possibly lethargy
-more difficult to come by than a-dex or letro

Appropriate uses for Exemestane:

#1) on cycle estrogen control - that's right, any and all estrogen related problems can and should be corrected with this compound, from gynecomastia to acne to bloat exemestane is a panacea, run it at 12.5mg e4d for gynecomastia protection and bloat control, or run it at 25mg ED for pre-contest or for gynecomastia sensitive individuals or moon face. the beauty of aromasin is it's okay to use preventatively and not just as spot treatment for gynecomastia as it doesn't hurt gains nearly to the degree that other Anti-E's do, i'd still recommend using Anti-E's only if you need them, but if you must use one throughout your cycle, you couldn't pick a better compound to use.

#2) PCT. Aromasin is the premier PCT drug in my experience... honestly PCT is kind of fun with aromasin (maybe that's a stretch) but it's a breeze compared to clomid/nolva and significantly better than a-dex (more powerful and fewer sides) it works excellently with HCG - human chorionic gonadotropin - and keeps the extra aromatization from the HCG - human chorionic gonadotropin - injects at bay (you can even run higher dosages of HCG - human chorionic gonadotropin - above 500iu/inject) and another bonus is since it's safe and comfortable to run for longer periods of time, you can stretch your PCT out to 6 or 8 weeks for suppressive cycles to make sure you get everything back in full working order

#3) gynecomastia reversal - in conjunction with a selective estrogen receptor modulator (raloxifene or tamoxifen) and/or a dihydrotestosterone derived compound aromasin can be effective in reversing/reducing existing gynecomastia

#4) off cycle testosterone boost - sometimes if i dont feel like running a cycle but still want a little extra kick i'll take 25mg EOD for 4-6 weeks, gains aren't improved all that greatly but significantly, but i do it more for the Libido/mental effects anyways.

#5) hypogonadism - so you're getting older, you've been cycling since you were 21 and your natty test levels just never get back in the good range, but you don't wanna go HRT??? aromasin will get you back in the game without having to take the plunge for HRT.

inappropriate uses for exemestane:

#1) giving your gf hot flashes

well that's my write up for the best Anti-E out there, i'm sure i left some stuff out, if anyone has any questions feel free to PM me or ask on this thread