Letrozole (Femara)

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TweetLetrozole (Femara)
Letrozole is the chemical name of Novartis selective third generation aromatase inhibitor (AI), a drug that works by blocking the aromatase enzyme responsible for the production of estrogen.

In clinical use, Letrozole is primarily administered to halt the progression of breast cancer in women. It is generally used as part of an aggressive treatment in post-menopausal women, to fight and reverse the spread of breast cancer after other treatments (such as Tamoxifen therapy) has failed. Its probably the most efficient product on the market for this purpose (5). Letrozole is very similar in both structure and action to its AI predecessor Arimidex.

In athletics and bodybuilding, it is used as an ancillary compound within anabolic steroid cycles for its estrogen reducing properties, and has the additional benefit of modestly increasing testosterone levels. Many anabolic steroids aromatize (convert to estrogen via the aromatase enzyme), a process that is responsible for many of the undesirable side effects which accompany anabolic steroid use such as acne, gynecomastia, water-retention, etc.

Letrozole also does quite a few things that would be of interest to both bodybuilders and athletes. Firstly, it has been shown to reduce estrogen levels by 98% or greater (1). In at least one documented incident, Letrozole reduced test subject estrogen to undetectable levels, while increasing LH, FSH and SHBG (4). For the bodybuilder, less estrogen in the body means less chance of estrogen-related side effects. This makes Letrozole an appropriate choice for even the heaviest bulking or cutting cycles, including those which incorporate harsher androgens. Also, if you are a competitive bodybuilder, Letrozole is a must have product for contest preparation as no other ancillary compound supports the coveted dry and tight appearance quite as well.

Testosterone Treatment only $199/month All-IncludedAn effective dose of Letrozole is .25 to .5mg/day. I use .25mgs/day, but be forewarned, if you go over this amount it can kill your sex drive. Also worth noting is Letrozoles substantial estrogen rebound effect that occurs after discontinuation. Maximum inhibition of the aromatase enzyme has been cited at doses as low as 100 mcg. (2)

Its effects on serum lipids including cholesterol, both HDL and LDL are, in the words of one researcher: "inconsistent." However, you could certainly suffer an impaired lipid profile and immune system if estrogen levels remain too low for long periods of time.

As previously mentioned, Letrozole can be used to raise LH and FSH, these are hormones which signal your testes to produce more testosterone. (6) These properties mean that Letrozole can be used for post-cycle therapy (PCT), and I have successfully used it for this purpose. However, for various reasons, Tamoxifen is a better PCT choice.

How good is Letrozole when compared with Aromasin (Exemestane) and Arimidex (Anastrozole), its primary rivals? Letrozole is 10-20x more potent than Anastrozole, and about as potent (but with a slightly different mechanism) as Exemestane. It also long-lasting. Letrozole has a whopping 2-4 day half-life, and youll need to take Letrozole for approximately 60 days (with wild variance of 2-6 weeks) to achieve a steady blood plasma level (8).

Those are impressive numbers, but heres one of the most interesting things about Letrozole:

It may reduce/eliminate/reverse existing gynecomastia!

In a study conducted on mice (and yes, I know its not perfect), gyno-like changes in the mammary gland were totally destroyed! Heres a direct quote from that study:

Our results also indicate aromatase overexpression-induced changes in mammary glands can be abrogated [destroyed] with very low concentrations of the aromatase inhibitor, letrozole.(7)

In addition, both I and a friend successfully used Letrozole to eliminate our gyno while both using 2.5mgs/day, tapering down to .25mgs/day, and then finally off. The gyno never returned for either of us.

Based on its availability and cost (when you consider the fact that .25mgs/day is more than enough protection from estrogen-related sides on most cycles), not to mention its overall utility for a variety of functions (destroying gyno, preventing estrogenic sides, and for PCT), Id say that this stuff is pretty great.

Letrozole References:
1. Clin Cancer Res. 2005 Apr 15;11(8):2809-21.
2. J Clin Endocrinol Metab. 1995 Sep;80(9):2658-60.
3. Eur J Obstet Gynecol Reprod Biol. 2002 Nov 15;105(2):161-5
4. Epilepsy Behav. 2004 Apr;5(2):260-3
5. Semin Oncol. 2004 Dec;31(6 Suppl 12):3-8.
6. Diabetes Obes Metab. 2005 May;7(3):211-5.
7. J Steroid Biochem Mol Biol. 2001 Dec;79(1-5):27-34. Aromatase overexpression transgenic mice model: cell type specific expression
and use of letrozole to abrogate mammary hyperplasia without affecting normal physiology.
8. (Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S.).

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TweetFemara (Letrozole)

Letrozole - Femara - Fempro
Femara (letrozole) is a type II (non-steroidal) third generation aromatase inhibitor. Clinically it is used to treat postmenopausal women with either estrogen receptor positive or estrogen receptor unknown breast cancer.
In women, tumors that contain estrogen receptors are classified as estrogen receptor-positive (ER+) tumors. For Letrozole to be prescribed, a given tumor must have been diagnosed as estrogen receptor positive or estrogen receptor unknown.
In the world of bodybuilding it is used to reduce or eliminate excess estrogen caused by the use of aromatizing steroids.
Background
Letrozole was originally sold under the brand name Femara, and produced by the pharmaceutical house Novartis. It was patented on July 25th, 1997.
Action
Letrozole is known as a type II aromatase inhibitor, meaning, in simplest terms that it attaches to the aromatase enzyme and prevents it from converting androgens to estrogen. In slightly more complex terms, estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme, and letrozole actually inhibits the production of estrogens in by competitive, (reversible) binding to the heme of the relevant cytochrome P450 unit.
Technical Data
Letrozole is currently the most powerful aromatase inhibitor available. In women with breast cancer, it has been shown to reduce estrogen levels by 98% or more (1). However, it’s use and benefits are not limited to eliminating estrogen in women.
In one male test subject Letrozole was able to reduce estrogen levels to undetectable levels (2), and in another clinical study done on both young and elderly men, intravenous administration of Letrozole lowered Estrogen by 46% in the young men tested, and 62% in the elderly subjects. Because estrogen is part of the negative feedback loop of the HPTA, Letrozole (and other anti-estrogens) are able to raise testosterone in male subjects. Letrozole was studied in men, and found to significantly increase LH levels to a 339 and 323% in the young and the elderly, respectively and Testosterone by 146 and 99%, respectively. (3) Letrozole was also able to produce a peak LH response to Gonadatropin Releasing Hormone equal to a 152 and 52% increase from baseline in either young or older men, respectively (3). In a similar study 0.02 mg of Letrozole increased testosterone by 45% after 2 days. (4) That same twenty micrograms of Letrozole was also enough, in one study done on men, to reduce estrogen levels by roughly a third. (4)
Letrozole has a 2-4 day half-life, and it needs to be taken for up to 60 days to get a steady blood plasma level (5).
Letrozole was used in a rodent study to effectively destroy (benign) breast tissue tumors (6), which may potentially indicate its use in males attempting to remove gynecomastia (aka gyno).
As estrogen is also a factor in stopping linear bone growth, Letrozole is currently being examined for potential use in delay of growth seen in children.
User Notes
In the world of bodybuilding where more is often thought to be better, Letrozole stands almost alone as an exception to that rule. Estrogen is necessary for healthy immune function, healthy cholesterol levels, joint health, cognitive function, and even aids in muscle growth. In my own experience as well as the experience of many bodybuilders and athletes I’ve worked with, Letrozole simply causes estrogen to be reduced to levels too low to function properly. Personally, I suffered a near career-ending knee injury while using 2.5mgs a day of this stuff, and had one of the worst (and longest) bout with the flu I’ve ever had. In my own particular case, I had been using it to eliminate gyno (which it did). I started at a dose of 2.5mgs/day and reduced it by .25mgs every week until the gyno showed no signs of coming back. Unfortunately, this compromised my immune system and joint integrity.
For most recreational steroid users, Letrozole is going to be too harsh, and cause too many problems. Still, people can use it effectively if they don’t use the manufacturer’s clinical dose (2.5mgs) and instead keep their dose to .25-1mg. There are, however, better choices for an anti-estrogen. I should mention that using Letrozole at such a low dose does happen to make it a very good economic choice compared with other aromatase inhibitors.
For pre-contest bodybuilders, Letrozole is almost a necessity to eliminate water retention and achieve the ripped look necessary to compete in today’s bodybuilding world. However, in my experience, it is only necessary to be used for the last 4-6 weeks, to eliminate excess estrogen and water retention. After using Letrozole I recommend staying away from any estrogen suppression for at least a month to try to normalize the body.
Letrozole is the chemical name of active ingredient in Femara. Femara is a registered trademark of Novartis Pharmaceuticals Corporation in the United States and/or other countries.
References
Clin Cancer Res. 2005 Apr 15;11(8):2809-21.
Epilepsy Behav. 2004 Apr;5(2):260-3
J Clin Endocrinol Metab. 2005 Oct;90(10):5717-22. Epub 2005 Jul Comparative assessment in young and elderly men of the gonadotropin response to aromatase inhibition. T’Sjoen GG, Giagulli VA, Delva H, Crabbe P, De Bacquer D, Kaufman JM.
Open dose-finding study of a new potent and selective nonsteroidal aromatase inhibitor, CGS 20 267[Letrozole], in healthy male subjects PF Trunet, P Mueller, AS Bhatnagar, I Dickes, G Monnet and G White. Research and Development Department, CIBA-GEIGY Limited, Basel, Switzerland.
Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S. Department of Endocrinology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
J Steroid Biochem Mol Biol. 2001 Dec;79(1-5):27-34. Aromatase overexpression transgenic mice model: cell type specific expression and use of letrozole to abrogate mammary hyperplasia without affecting normal physiology

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TweetLetrozole

(femara)

Letrozole (Femara) is the chemical name of Novartis´ selective third generationAromatase Inhibitor (AI). This drug was developed to fight breast cancer by inhibiting the aromatization. It is usually used as a part of an aggressive treatment in post-menopausal women, to fight and reverse the spread of breast cancer after other treatments (such as Tamoxifen therapy) has failed. It´s probably the most efficient product on the market for this purpose currently (5) It is very similar in structure and action to it´s predecessor Arimidex.

Letrozole (Femara) also does quite a few things which would be of interest to both bodybuilders and athletes. Firstly, it has been shown to reduce estrogen levels by 98% or greater (1). In at least one documented incidence, Letrozole (Femara) reduced estrogen in the test subject to undetectable levels, and increased LH, FSH and SHBG (4). Clearly this is all of interest to bodybuilders, as less estrogen in the body means less chance of certain side effects such as water-retention, Gynocomastia, and acne. This makes Letrozole (Femara) an appropriate choice for even the heaviest bulking or cutting cycles including harsh androgens. Also, if you are a competitive bodybuilder, Letrozole (Femara) is a must have product for contest prep; no other Ancillary compound will produce a dry and tight look like Letro will.

An effective dose of Letrozole (Femara) is .25-.5mg/day (I use .25mgs/day), but be forewarned, if you go over that amount, it can kill your sex drive. Also worth noting is that there´s a rebound effect on your estrogen when you come off Letrozol. Maximum inhibition of the aromatase enzyme has been found to happen at doses as low as 100mcg! (2)

Letrozole (Femara)´s effects on serum lipids (cholesterol, both HDL and LDL) are, in the words of one researcher: "inconsistent. " Clearly, however, you´ll eventually suffer an impaired lipid profile and immune system if you keep your estrogen levels too low for too long. Your sex drive will also probably suffer from extraordinarily low levels of estrogen present.

As previously mentioned, Letrozole (Femara) can be used to raise LH and FSH (which are hormones which signal your testes to produce more testosterone). It also, of course, will raise your testosterone levels (6) via this mechanism. Again, this is of interest to athletes and bodybuilders for obvious reasons. Letrozole (Femara), of course, can be used for post-cycle-therapy (PCT) to raise test levels, but for various reasons, Tamoxifen may be a better choice. Still, I have successfully used Letrozole (Femara) for this purpose.

How good is this compared with Aromasin and Arimidex, it´s too other main rivals? Well, In non-cellular systems, Letrozole (Femara) is 2-5 times more potent than anastrozole and exemestane in its inhibition of the aromatase enzyme and activity, and in cellular systems it is 10-20x more potent! It also lasts quite a long time in your body,but takes awhile to get going& Letrozole (Femara) has a whopping 2-4 day (!) ½ life, and you need to take Letrozole (Femara) for 60 days to get a steady blood plasma level (8).

Those are impressive numbers, but here´s one of the most interesting things about Letrozole (Femara):

It may reduce/eliminate/reverse existing gynocomastia!
In a study conducted on mice (*no, I know it´s not perfect), gyno-like-changes in the mammary gland were totally destroyed! Here´s a direct quote from that study:
"Our results also indicate aromatase overexpression-induced changes in mammary glands can be abrogated [destroyed] with very low concentrations of the aromatase inhibitor, Letrozole (Femara)."(7)
In addition, I´ve used Letro to get rid of my own gyno, as has a friend of mine, and we both used it at a dose of 2.5mgs/day, tapering down to .25mgs/day, and then finally off..the gyno never returned in both our cases.

I´d say that this stuff is pretty great, considering its availability and cost (when you consider the fact that .25mgs/day is more than enough protection from estrogen-related sides on most cycles), not to mention it´s overall utility for a variety of functions (destroying gyno, preventing estrogenic sides, and for PCT).

References:

Clin Cancer Res. 2005 Apr 15;11(8):2809-21.
J Clin Endocrinol Metab. 1995 Sep;80(9):2658-60.
Eur J Obstet Gynecol Reprod Biol. 2002 Nov 15;105(2):161-5
Epilepsy Behav. 2004 Apr;5(2):260-3
Semin Oncol. 2004 Dec;31(6 Suppl 12):3-8.
Diabetes Obes Metab. 2005 May;7(3):211-5.
J Steroid Biochem Mol Biol. 2001 Dec;79(1-5):27-34. Aromatase overexpression transgenic mice model: cell type specific expression and use of Letrozole (Femara) to abrogate mammary hyperplasia without affecting normal physiology.
(Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S.).