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    Senior Member coltmc4545's Avatar
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    Exclamation Half lives of AI's

    Ok so I'm writing this thread due to seeing a ton of people lately running Aromasin EOD. We need to think of half lives of AI's just like we think about the half lives of esters of gear. Some of this is copy and paste info as I'm too lazy to write everything out in my own words, and some of this is in my own words. So here we go....

    First let's define what an AI is and what they're used for.

    AI is short for Aromatase Inhibitor. Aromatase Inhibitors prevent the conversion of androgens into estrogen in fat, muscle, breast, and brain. Aromatase inhibitors work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization. As breast tissue is stimulated by estrogens, decreasing their production is a way of suppressing recurrence of the breast tumor tissue. Estrogen is produced and acts locally in these tissues, but any circulating estrogen, which exerts systemic estrogenic effects in men and women, is the result of estrogen escaping local metabolism and spreading to the circulatory system.

    What are the different types of AI's?

    There are many different AI's out there. The most common used in the BB world are exemestane (Aromasin or "stane"), anastrozole (arimidex or "adex"), Letrozole (femera or "letro") Some people might argue that tamoxifine, or nolvadex, can be used as an AI. Nolva is NOT an AI. Nolva is a SERM. It has been used in plenty of studies and was the go to drug for years for gyno help in the BB world. It still is used by BB for reducing gyno but has actually been shown in recent studies to not affect steroid induced gyno as well as it has in gyno caused by puberty in males. Which brings me to another point, taking Nolva will not prevent high e. SERMs DO NOT lower estrogen. SERMs block estro from attaching to the breast tissue. They sit in the estrogen receptor and there is no room for the estrogen to attach to the receptor making it impossible for the cells to recieve estrogens signals to grow and multiply. After all, were not just trying to prevent gyno, were trying to control our estrogen levels which we do by taking AI's.

    Breakdown of types of AI's

    Aromasin- Exemestane is an irreversible, steroidal aromatase inactivator, structurally related to the natural substrate androstenedione. It acts as a false substrate for the aromatase enzyme, and is processed to an intermediate that binds irreversibly to the active site of the enzyme causing its inactivation, an effect also known as "suicide inhibition." In other words, Exemestane, by being structurally similar to the target of the enzymes, permanently binds to those enzymes, thereby preventing them from ever completing their task of converting androgens into estrogens. No need to taper dosage on stane as there is no risk of estro rebound. In laymans terms it kills estrogen.

    Arimidex- Anastrozole binds reversibly to the aromatase enzyme through competitive inhibition, inhibits the conversion of androgens to estrogens in peripheral tissues (outside the CNS), and a few CNS sites in various regions within the brain. Adex needs to be tapered down as it can cause an estro rebound as it doesn't kill estro, it attaches itself to it.

    Letrozole- Letro, just like arimidex, reversably binds to the aromatase enzyme. It also needs to be tapered. Letro is probably the most toxic and harshest of the 3. Be careful with letro as it will put you on your ass.

    What are the half lives of these AI's and how often should you take them?

    Here's where we get to the point of all this jiber jabber I have posted.

    Letrozole -Letro's half life is about 2 days. It reaches steady blood plasma levels in 2-6 weeks (study showed this at a daily dose of 2.5mg although I couldn't imagine taking this stuff at 2.5mg ed for 6 weeks) So basically you can dose letro eod although when I read the word "about" 2 days, personally I'd dose everyday. Like I said above, letro is no joke. If using for an AI, start at a VERY VERY low dose like .25 mg ed. This stuff will crash your E and have your joints feeling like they're made of concrete. It's also been shown to increase the risk of osteoperosis and has been shown to weaken bone structure. Also don't forget to taper letro so you don't get an estro rebound!!

    Arimidex - Adex's half life is shown to be 48.6 hours which means it is ok to dose adex EOD (every other day). A usual starting dose is .25-.5 mg EOD. Just like letro, taper down once coming off so you don't rebound.

    Aromasin - Stane's half life is 27 hours which means to achieve stable blood plasma levels, it needs to be dosed ED (everyday) A usual starting dose is 12.5mg ed. If I run it all the way through cycle instead of just starting when signs of high e are noticed, I start at 6.25mg ED. You do not need to taper with aromasin as like was shown above, it's a suicidal inhibitor and you won't get any estro rebound. Aromasin is the AI of choice for me for this reason.



    I hope this info clarifys things for people. Like I said in the beginning, think of AI's, SERMs, hell even peptides and SARMs, the same way you think regarding esters in different compounds of gear. The goal is to achieve stable blood plasma levels. We do this by recognizing the half lives of these chemicals. The more stable our blood plasma levels, the greater the effect of whatever chemical we're using has AND the less chance we have for side effects from that chemical.

    -Colt

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    For a lot of us 12.5 mg a day is overkill.

    Same as test injection people are too concerned with stable levels. Your natural levels are NOT stable.

    There is a saying about the best laid plans of mice and men.

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    Member Jawey's Avatar
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    Re: Half lives of AI's

    Thanks Colt, very informative. Kinda sucks I only have 12.5mg caps of Aromasin.. Guess you gotta work with what you got!

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    Senior Member coltmc4545's Avatar
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    Re: Half lives of AI's

    Originally Posted by 69nites View Post
    For a lot of us 12.5 mg a day is overkill.

    Same as test injection people are too concerned with stable levels. Your natural levels are NOT stable.

    There is a saying about the best laid plans of mice and men.
    This is why I prefer stane in liquid form over pill. I can easily dose at 6.25 Ed and I don't crash my e.

    I think people should be concerned with stable levels when putting things in our bodies that aren't naturally orcuring. Maybe not to the point of making threads with spreadsheets on em lol It's the same reason we tell people not to frontload, or increase dosages of test from 500 to 750, because the spike will cause more sides. I'm not just speaking about bro science and what I saw so and so say on this or that board, I'm speaking from my own experience.

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    Senior Member coltmc4545's Avatar
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    Re: Half lives of AI's

    Originally Posted by Jawey View Post
    Thanks Colt, very informative. Kinda sucks I only have 12.5mg caps of Aromasin.. Guess you gotta work with what you got!
    You can cut open your caps, split the powder in equal piles, stir a pile into some oj or Gatorade. That takes you down to 6.25. There's a way around almost every obstical brotha!

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    Elite TheLupinator's Avatar
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    Re: Half lives of AI's

    Aromasin is the superior AI...
    I <3 My Source

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    Member stb1041's Avatar
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    Re: Half lives of AI's

    How do so many people use Aromasin EOD successfully? There is a lot of debate about the need to use exemestane ED even though the half life is so short. The drugs effects can last longer even after the drug is not active in the body.


    Not trying to argue or say that u are incorrect, just wanting an answer to this

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    Elite Shane1974's Avatar
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    Re: Half lives of AI's

    This AI business is a complicated matter to me.

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    Senior Member Omegareign's Avatar
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    Re: Half lives of AI's

    Everyone is different though. I run my aromasin at 25mg ED, for one, cause Ive gotten gyno before and never want it again, for two, we all know these research companies can be unreliable with dosages so a little extra won't kill you. Find your sweet spot.

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    Senior Member Curiosity's Avatar
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    Re: Half lives of AI's

    Originally Posted by coltmc4545 View Post
    This is why I prefer stane in liquid form over pill. I can easily dose at 6.25 Ed and I don't crash my e.

    I think people should be concerned with stable levels when putting things in our bodies that aren't naturally orcuring. Maybe not to the point of making threads with spreadsheets on em lol It's the same reason we tell people not to frontload, or increase dosages of test from 500 to 750, because the spike will cause more sides. I'm not just speaking about bro science and what I saw so and so say on this or that board, I'm speaking from my own experience.
    Heyyyyy..... ha ha.

    I've been taking Aromasin @ 12.5 EOD and honestly its working fine, I would prefer to dose it at 6.25 ED but I have 12.5 mg caps. I could split it up like you suggested though. On the other hand, however, as a suicidal inhibitor you could possibly expect a dose of it to keep your aromatase levels low for a period of time after the compound itself is out of your system. I'm not sure how long it takes for the body to produce more aromatase to replace what was de-activated by the aromasin. Anyone have any knowledge of that?

    Anyway, thanks for the post, maybe I'll start splitting up my caps and see how it goes.

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    Originally Posted by coltmc4545 View Post
    This is why I prefer stane in liquid form over pill. I can easily dose at 6.25 Ed and I don't crash my e.

    I think people should be concerned with stable levels when putting things in our bodies that aren't naturally orcuring. Maybe not to the point of making threads with spreadsheets on em lol It's the same reason we tell people not to frontload, or increase dosages of test from 500 to 750, because the spike will cause more sides. I'm not just speaking about bro science and what I saw so and so say on this or that board, I'm speaking from my own experience.
    AI are to prevent estrogen buildup. Unless your levels are getting jacked up high every single day its not necessary to dose it every day.

    Your concern is not the amount of aromasin in your system, its the amount of estrogen. If the goal is to reduce your day to day estrogen levels aromasin eod works just as well as ed. No one gets a roller coaster of sides from aromasin unless they are lowering their estrogen levels too much.

    My blooodwork always shows in range estrogen at 12.5 mg eod. For me THAT is all that matters.

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    Re: Half lives of AI's

    Originally Posted by 69nites View Post
    For a lot of us 12.5 mg a day is overkill.

    Same as test injection people are too concerned with stable levels. Your natural levels are NOT stable.

    There is a saying about the best laid plans of mice and men.
    I agree with this ^^^^ and I agree with Colt.
    Because it is such a highly effective suicide inhibitor, exemestane does NOT need (IMHO) to take it every day unless you want your estrogen to be too low. I have learned that for me, I am better off with 12.5 mg eod or even 25mg every third day.

    I do agree that with a typical AI a more frequent dose can be beneficial since they compete for the same binding enzymes and receptors as the test that would be converted to estrogen do.

    As for Letro I would never advise taking it unless you have obvious symptoms of gyno and then it is effective treatment when tapered up-stabilized-and tapered down. Keep in mind that everyone's body is a little different and we may differ on what works best for us.

    Good information and a great post Colt.

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    Member stb1041's Avatar
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    Re: Half lives of AI's

    This was a post made by Chip Wadowski on this topic:

    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 sex hormone binding globulin 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.

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    Senior Member coltmc4545's Avatar
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    Re: Half lives of AI's

    I'm not talking a rollercoaster of sides from aromasin. I'm talking about your estro rollercoastering. You can't tell me that estro levels don't fluctuate on a day to day basis. Go get bloodwork done on cycle one day then go back the next day and get another draw. The numbers will differ. I'm not saying they'll be a huge difference, but there will be one. Let me ask you this, when running test e do you inject once a week or twice a week? After all the half life of e is 7 days correct? 10 with test c. So why inject twice a week with long esters if the relativity of half lives and blood stability levels don't have anything to do with side effects? Why do we inject long esters twice a week? Some even go as far as M/W/F. Hell I've seen a vet on ology talk about how he injects long esters ED. We do this to create more stabile blood plasma levels which in turn produces less peaks and valleys which means what? Less side effects. I'm not saying your point is wrong, it works for you and that's what matters to you. This is what works for me. I just don't see why people talk about stabile blood levels and half lives of gear but then dose something with a little over a full days half life eod. That would be like pinning test e once every 2 weeks. After all if stanes half life is about 24 hours and you take it every 48 hours that would be the same as pinning test e that has a half life of 7 days every 14 days. My point of this write up isn't to say your wrong and do it this way, it's more to start getting people to think about half lives in everything they use, not just what oral or oil they're using.

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    Originally Posted by coltmc4545 View Post
    I'm not talking a rollercoaster of sides from aromasin. I'm talking about your estro rollercoastering. You can't tell me that estro levels don't fluctuate on a day to day basis. Go get bloodwork done on cycle one day then go back the next day and get another draw. The numbers will differ. I'm not saying they'll be a huge difference, but there will be one. Let me ask you this, when running test e do you inject once a week or twice a week? After all the half life of e is 7 days correct? 10 with test c. So why inject twice a week with long esters if the relativity of half lives and blood stability levels don't have anything to do with side effects? Why do we inject long esters twice a week? Some even go as far as M/W/F. Hell I've seen a vet on ology talk about how he injects long esters ED. We do this to create more stabile blood plasma levels which in turn produces less peaks and valleys which means what? Less side effects. I'm not saying your point is wrong, it works for you and that's what matters to you. This is what works for me. I just don't see why people talk about stabile blood levels and half lives of gear but then dose something with a little over a full days half life eod. That would be like pinning test e once every 2 weeks. After all if stanes half life is about 24 hours and you take it every 48 hours that would be the same as pinning test e that has a half life of 7 days every 14 days. My point of this write up isn't to say your wrong and do it this way, it's more to start getting people to think about half lives in everything they use, not just what oral or oil they're using.
    I have injected test e once a week and saw no noticeable difference from 2x.

    I take my dbol in one large dose preworkout. I take tne on workout days only.

    Your levels are supposed to fluctuate. People are getting all knitpicky about their stable levels. Your body does not produce stable levels. It produces hormone spikes.

    Stable levels IME do not produce as good of results as hormone spikes.

    If my estrogen is in range on every blood test I take I don't give a shit about the variance.

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    Senior Member Curiosity's Avatar
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    Re: Half lives of AI's

    Very interesting thread guys, good discussion!

    I have been wondering about this for a while since I've been taking my aromasin EOD for the last few weeks due to the dosing of the caps I have, and after reading this whole thread I have to conclude that EOD dosing is not going to cause significant estro fluctuations or problems.

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    Re: Half lives of AI's

    Originally Posted by coltmc4545 View Post
    This is why I prefer stane in liquid form over pill. I can easily dose at 6.25 Ed and I don't crash my e.

    I think people should be concerned with stable levels when putting things in our bodies that aren't naturally orcuring. Maybe not to the point of making threads with spreadsheets on em lol It's the same reason we tell people not to frontload, or increase dosages of test from 500 to 750, because the spike will cause more sides. I'm not just speaking about bro science and what I saw so and so say on this or that board, I'm speaking from my own experience.
    Not sure if Im offended? or flattered?

    Just kidding. Great post colt!

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    Senior Member coltmc4545's Avatar
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    Re: Half lives of AI's

    To each his own.

    Not sure why you keep referencing your body doesn't produce stabile levels 69. Your body doesn't produce dbol or tne or test levels over 1500 either. When your body's natural hormone levels fluctuate it also fights to bring itself back to homeostasis also correct? When your shut down then that's not happening so we do it ourselves with AI's and test. Like I said, this is more so people get an understanding of half lives, and that everything were putting in our bodies has them. Plus it seems alot of research companies put out tablets and not liquid. Liquids of course easier to split dosing up into smaller doses. So people with tabs or caps, not wanting to crash thier e, dose eod.

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    Originally Posted by coltmc4545 View Post
    To each his own.

    Not sure why you keep referencing your body doesn't produce stabile levels 69. Your body doesn't produce dbol or tne or test levels over 1500 either. When your body's natural hormone levels fluctuate it also fights to bring itself back to homeostasis also correct? When your shut down then that's not happening so we do it ourselves with AI's and test. Like I said, this is more so people get an understanding of half lives, and that everything were putting in our bodies has them. Plus it seems alot of research companies put out tablets and not liquid. Liquids of course easier to split dosing up into smaller doses. So people with tabs or caps, not wanting to crash thier e, dose eod.
    I keep referencing because people talk about stable levels like its unhealthy to have unstable levels.

    I dislike regurgitation of BS info. If eod dosing keeps your estrogen levels in normal range at all times why do you care about making something simple complicated?

    I think these kinds of graphs are cool for looking at a test blend or determining how long your kick start should be but that's about it.

    Looking at things like this is what they do before clinical trials. Then they determine based on the real life use what is the best way to administer. Why take a step back when you already know what works?

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    Senior Member coltmc4545's Avatar
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    Re: Half lives of AI's

    People are talking about stable levels because maybe possibly they get side effects from blood levels fluctuating up and down. Maybe you don't and you're lucky. Good for you. Me on the other hand, I have horrible bacne which I've been able to manage pretty well this cycle from pinning Ed aka keeping my blood levels stable. If you disagree, that's fine. Like I said to each his own. What works for you might not work for me. How is my post regurgitating bs info? Everything I posted is backed up by actual science, not bro science on a board.

    Show me a clinical trial of use of AI's that they dosed aromasin eod though. Everyone that I read while writing the initial post talked about dosing 25mg ED. You can't say they do this before clinical trials and then find out what works because I have yet to read an actual clinical trial on aromasin where it wasn't administered ED. I've read nothing but posts on boards from bro's aka bro science about dosing eod. If its a step backwards to say to dose Ed then it's also a step backwards giving people advice on pinning LE's twice a week also. I don't see how anything I posted was regurgitating bs info when all the info I posted is backed up by actual clinical studies. Not by a dude on a steroid board saying it works for him. I'll take science over broscience any day.

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