Letrozole is considered the most powerful aromatase inhibitor (AI), developed and marketed in the late 90s under the trade name Femara, with therapeutic indication for the treatment of advanced breast cancer in postmenopausal women.

Letrozole, like anastrozole, is a third generation non-steroidal AI (the most potent and selective among AIs), but it is considered to be more potent than anastrozole. The usual dose for the treatment of breast cancer is 2.5 mg per day (one tablet), but even at doses less than 0.5 mg / day letrozole can reduce estradiol concentrations to undetectable levels. Bodybuilders like to use this drug when they use high doses of testosterone or in pre-contest periods, as a reduction in estrogen can help decrease water retention. But caution is needed with this drug, as very low levels of estrogen can negatively affect sexual function (libido, erection), lipid profile, joints and also increase fatigue. Another problem with this drug is the potential rebound effect of estrogen after discontinuing use, so the weaning technique (gradual withdrawal of the drug) is recommended to try to control this problem and even the use of a SERM (tamoxifen or clomiphene) can help in controlling the rebound effect of estrogen.

I found no basis for the idea that letrozole can regress a consolidated gynecomastia (when fibrous breast tissue). Particularly, I consider the use of letrozole to be more risky compared to other aromatase inhibitors and it would be strongly recommended to follow laboratory tests when using this drug to reduce estradiol levels, with some gurus and experts recommend maintaining an estradiol in the range of 20-30 mg / dL to avoid adverse effects, although I find higher concentrations of estradiol acceptable when testosterone and androgenic steroid levels are high.

Leave a comment