A final note I would like to make in this article is about the usage of SERMs during an anabolic steroid cycle. SERMs, like tamoxifen, function as a competitive antagonist. That means that they need to “compete” with other ligands of the estrogen receptor, such as estradiol, for binding. Without going into too much detail, that means you need more tamoxifen to occupy the same number (or concentration I should say) of receptors if there’s also a whole lot more estradiol around. Which is, of course, the case when injecting large quantities of testosterone. Concentrations of over 4 times the maximum reference range aren’t unheard of. As such, tamoxifen might be required in higher quantities too to reach sufficiently high concentrations to effectively compete with the increased concentration of estrogen for binding. While under physiological circumstances 10 to 20 mg daily is plenty, one might need dosages of around 40 mg daily while on a high-dosed cycle with an aromatizing androgen. However, this is speculation from my part as there’s no good data on this. But this might help explain why sometimes during an AAS cycle, tamoxifen might not be (sufficiently) effective to prevent gynecomastia from developing.
thinksteroids.com
