T Nation

Which is Stronger: 1mg of Anastrozole or 1mg of Letrozole?

All the articles I read about the comparison between the two substances use 1mg of Anastrozole versus 2.5mg of Letrozole to demonstrate the effectiveness. The conclusion, obviously, is that Letrozole is much more potent, however the dosage is always 2.5x higher than that of Anastrozole.

But if you compare 1mg vs 1mg equally, Letrozole is still more potent? I didn’t find any article on that.

All I know is the more serious the disease whether its a bad case of gyno, or breast cancer they are prescribed letrozole, and not anastrozole. That doesn’t really answer your question scientifically, though.

Do you want to know for your general knowledge or are you trying to solve a bad case of gyno?

As the saying goes there is more than one way to skin a cat. Regardless of which one is stronger you can tailor the result by how your body is responding to one drug, or the other. One might be better in theory, but in practice both might work, with a tailored dose.
I stay far away from both Anastrozole and letrozole, massive overkill for me if I want to stop high E2 symptoms.

Well, 1mg is 40% of 2.5mg, so .4 x 1mg is .4mg anastrozole, if you want a 1 to 1 comparison. But since Letro is much stronger in studies, I’d maybe say treat it more like 50-70%. So, my guess. 1mg letro is like .7mg anastrozol
Edit: I have no idea if this makes sense, but if you’re trying to figure out how to dose your letro based on how one would dose anastrozole, I guess I’d start there

There is no data in men with a dosage of 1 mg letrozole. However, there is with 2.5 mg daily:

G. G. T’sjoen, V. A. Giagulli, H. Delva, P. Crabbe, D. De Bacquer, and J.-M. Kaufman. Comparative assessment in young and elderly men of the gonadotropin response to aromatase inhibition. The Journal of Clinical Endocrinology & Metabolism, 90(10):5717–5722, 2005.
G. Raven, F. H. de Jong, J.-M. Kaufman, and W. de Ronde. In men, peripheral estradiol levels directly reflect the action of estrogens at the hypothalamo-pituitary level to inhibit gonadotropin secretion. The Journal of Clinical Endocrinology & Metabolism, 91(9):3324–3328, 2006.

It roughly decreases estradiol by half at that dosage. But it could very well be it would do the same at 1 mg daily.

Either way, anastrazole also decreases estradiol roughly in half at both 0.5 mg and 1.0 mg daily:
N. Mauras, K. O. O’Brien, K. O. Klein, and V. Hayes. Estrogen suppression in males: metabolic effects. The Journal of Clinical Endocrinology & Metabolism, 85(7):2370–2377, 2000.

I’d say they have similar efficacy in men. In case you’re interested, I’ve covered the efficacy of aromatase inhibitors in a blog post: https://peterbond.org/post/the-efficacy-of-aromatase-inhibitors-in-men