Zewi
Well-known member
First you need to Understand a Type-II and Type-I aromatase inhibitor.
Type I inhibitors (like Aromasin) are actually steroidal compounds, while Type-II inhibitors (like Letro and A-dex) are non-steroidal drugs. Of course, there are some similarities between the two types of AIs…both type I & type II AIs mimic normal substrates (essentially androgens), allowing them to compete with the substrate for access to the binding site on the aromatase enzyme. After this binding, the next step is where things differ greatly for the two different types of AI’s. In the case of a type-I AI, the noncompetitive inhibitor will bind, and the enzyme initiates a sequence of hydroxylation; this hydroxylation produces an unbreakable covalent bond between the inhibitor and the enzyme protein. Now, enzyme activity is permanently blocked; even if all unattached inhibitor is removed. Aromatase enzyme activity can only be restored by new enzyme synthesis. Now, on the other hand, competitive inhibitors, called type II AI’s, reversibly bind to the active enzyme site, and one of two things can happen: 1.) either no enzyme activity is triggered or 2.) the enzyme is somehow triggered without effect. The type II inhibitor can now actually disassociate from the binding site, eventually allowing renewed competition between the inhibitor and the substrate for binding to the site. This means that the effectiveness of competitive aromatase inhibitors depends on the relative concentrations and affinities of both the inhibitor and the substrate, while this is not so for noncompetitive inhibitors. Aromasin is a type-I inhibitor, meaning that once it has done its job, and deactivated the aromatase enzyme, we don’t need it anymore. Letrozole and Arimidex actually need to remain present to continue their effects.http://thinksteroids.com/steroid-profiles/aromasin/
Arimdex binds to Estor but it will let go, thats why it’s a s a type-II aromatase inhibitor(just like letro but letro is 40% more effective in getting rid of estro)—Also a reminder if you are using Adex do not use Nolvadex as Nolvadex will reduce the blood plasma levels of Arimidex, it also does that to Letro also.
Where Aromasin is a Type-I aromastase inhibitor it binds to estor and does not let go. So if your prone to Gyno use Aromasin. Aromasin is about 65% efficient at suppressing estrogen it’s certainly a very powerful agent, There is also a decent amount of preclinical data suggesting that Aromasin has a beneficial effect on bone mineral metabolism that is not seen with non-steroidal agents, and it may also have beneficial effects on lipid metabolism that are not found in the non-steroidal Letro and A-dex
Also what makes Aromasin so great is Aromasin, also helps out your free to bound testosterone ratio by lowering levels of Sex Hormone Binding Globulin (SHBG), by about 20% SHBG is that nasty enzyme that binds to testosterone and renders it useless for building muscle. Because of this it makes Aromasin a great addition to your PCT.
IMO—Aromasin is the best AI to use because it’s a type 1 and its extra benefits, nothing wrong with Adex it has its place. And I do use it in short 8 week cycles for cutting as Adex will Dry you out.
Letro is hard and should only be used if you have signs of gyno not as your AI.