by Anthony Roberts
Most steroid users are at least somewhat aware of Arimidex (anastrozole). When it was first being studies for the purpose of reducing estrogen in women with breast cancer, it was prohibitively expensive at $5 for a single one-milligram tablet. A few years after the first studies were published, it became available through steroid sources and research chemical sites at a fraction of the legitimate prescription price.
Anastrozole reduces estrogen through competitive inhibition of the aromatase enzyme. This means that the drug binds to the enzyme itself, and blocks the enzyme’s ability to convert androgens to estrogens. In other words, it will prevent the conversion of natural or synthetic testosterone to estradiol, natural or synthetic androstenedione to estrone, and works to prevent exogenous aromatizing androgens from converting to an aromatized substrate (i.e. the conversion of Dianabol/methandrostenolone to 17 alpha methyl estradiol).
Anastrozole works very well at .5mg (*half a milligram) daily doses (which are roughly as effective as 1mg), is 85% bioavailablem and has a half-life of nearly two days (many bodybuilders only use it every other day for this reason). It’s a cheap and effective safeguard against estrogen-related side effects.
But it can also be used to prolong the effectiveness of testosterone during hormone replacement therapy, and I suspect that its use during a cycle will also make post-cycle therapy easier.
A 2014 study* on the combined use of testosterone replacement therapy (long-lasting implanted testosterone pellets) with anastrozole (1mg/day) versus testosterone without the aromatase inhibitor found that the combined group had significantly higher free and total testosterone levels (no surprise, since less was converted to estrogen). They also had lower estrogen levels (again, no surprise). So if we apply a little logic here, we could assume that consistently higher testosterone levels will take longer to decline whilst on hormone replacement therapy. And we’d be right – the average time until another dose was needed (defined as total testosterone dipping below 350ng/dl) was 198 days in the group receiving anastrozole vs. 128 days in the group that didn’t receive an aromatase inhibitor.
Naturally, I believe that similar results could have been had with a half milligram dose (again, the study used a full milligram).
But I think we can take this a bit further…
Estrogen is part of the negative feedback loop that inhibits the production of testosterone. So when your body produces testosterone, some of it gets converted to estrogen, and that estrogen signals your body to stop producing as much testosterone. This holds true whether we are talking about endogenous (natural) testosterone or exogenous (outside) testosterone (or any other anabolic steroid that we might inject, swallow, apply, implant, or otherwise consume).
Therefore, it stands to reason that if we limit this conversion to estrogen while on a cycle, it will not only give us higher testosterone levels, but should also inhibit some of the negative feedback loop, and make recovery of natural hormone levels easier, once we go off the cycle.
*J Sex Med. 2014 Jan;11(1):254-61. doi: 10.1111/jsm.12320. Epub 2013 Oct 9. Coadministration of anastrozole sustains therapeutic testosterone levels in hypogonadal men undergoing testosterone pellet insertion.Mechlin CW, Frankel J, McCullough A.