Letrozole is the third active substance in the novel selective aromatase inhibitors. It is used in school medicine, as well as anastrozole and exemestan, in advanced breast cancer in order to avoid the estrogen formation, and thus a progress of the disease. What letrozole (Femara) everything can do and what you should know about it is here:
Letrozole is primarily used in bodybuilding in the competition preparation / diet to achieve the lowest possible fat content. As estrogen is known to be a very potent hormone when it comes to storing and preserving body fat, the athlete must be strictly concerned about shifting the relationship between estrogens and androgens as much as possible in favor of the latter to ultimately obtain an optimal hardness and definition. The dosage used is as a rule at 2.5mg letrozole per day. Usually, a combination of aromatase inhibitors and estrogen receptor blockers (e.g. tamoxifen) is preferred in this phase to almost completely eliminate the estrogen effect, but this does not quite work because drugs such as tamoxifen block the estrogen receptors in the mammary glands, but not in the fatty tissue.
However, the active substance letrozole also promises advantages in normal anabolic treatments. Athletes, who are using strong aromatizing steroids with estrogen-related side effects such as increased fat and water storage, can significantly reduce these by the use of letrozole. However, it should be noted that the complete switching off of the estrogen in this phase also brings disadvantages, since estrogen itself is anabolic and also has a positive effect on the calcium and cholesterol levels. Therefore, those who largely eliminate estrogen in mass-building cures deprive themselves not only of some growth, but also endanger health. Such an approach is really just a matter of a sense before a competition, when it is no longer about a further muscle build-up, but exclusively about a hard, defined appearance. As a rule, in the mass phase, a moderate intake from a half to a whole tablet (equivalent to 1.25 - 2.5 mg) is sufficient every second day.
Women also benefit from the use of letrozole in the competition phase, which allows them to shift the estrogen / androgen ratio significantly in favor of the latter, thereby achieving a better form. However, an existing pregnancy should be excluded before use as letrozole may harm the fetus.
In post-cycle therapy, letrozole is also very active. As we know, the fastest possible uptake of body-borne testosterone production after a steroid cure is enormously important, and precisely at this point, letrozole provides outstanding services thanks to its pronounced estrogen-reducing properties. The dosage used is here 1.25 mg per day.
The question of the optimal application interval is quickly clarified. The manufacturer "Novartis" provides the half-life with approximately two days, so that the periods between the individual intakes can be correspondingly large. As a rule, letrozole, such as anastrozole and exemestan, is administered every day to every third day. The active substance is almost 100% absorbed after intake and can be taken without any problems with meals.
Letrozole blocks the activity of the aromatase enzyme which is responsible for the conversion of testosterone into estrogens. This effect is exploited by steroid-utilizing athletes and combined with letrozole with moderately to strongly aromatizing steroids, in order to largely prevent estrogen-induced side effects, such as increased fat and water storage.
Studies show that a single dose of 2.5 mg letrozole can lower estrogen levels by 75-78%, with the maximum effect being reached within 48-78 hours. Letrozole is therefore similar to the anastrozole in the effect and can be titrated as equivalent. As the effect of 2.5 mg letrozole and 1mg anastrozole is almost identical (<75-78% aromatase inhibition with letrozole vs. 70% with anastrozole) and there is no price difference, both preparations can be exchanged depending on availability. Letrozole does not come close to the strong effect of exemestan.
Competition male and female athletes use a 2.5mg tablet daily to suppress the aromatase activity as much as possible. In order to avoid estrogen-induced side effects during mass build-up cures with strong aromatizing steroids, from a half to a whole tablet usually suffices every other day. In the post-cycle therapy, 1.25 mg per day is usually used. Since the rebound effect can cause a rapid increase in the estrogen value in sudden discontinuation during a cure, a slow cessation of the active substance should be considered.
The potential side effects are similar to those of other aromatase inhibitors of the new generation. These include, in particular, hot flashes, sweating, thinning hair, headache, nausea, fatigue, depression and sleep disorders.