Letrozole (AKA Femara)

Overview and History of Letrozole

Letrozole (Femara) belongs to a category and class of medications known as aromatase inhibitors (AIs).

Aromatase inhibitors belong to a much broader class of medications known as anti-estrogens.

Another subcategory of drugs in the anti-estrogen category is known as selective estrogen receptor modulators (SERMs), such as Nolvadex and Clomid.

Aromatase inhibitors and SERMs make up the class of anti-estrogens.

Aromatase inhibitors differ significantly from SERMs in how they work and how they address estrogen regulation.

The misconception that SERMs like Nolvadex and Clomid act to lower estrogen levels should be addressed before delving further.

This is a myth that has only recently begun to die down in the anabolic steroid-using community, but it still persists.

SERMs act to block the action of estrogen by taking up receptor sites instead of estrogen, preventing estrogen itself from exerting its effects in breast tissue through receptor site binding.

Conversely, SERMs also act as estrogen at the receptor site on other cells in other parts of the body (e.g., the liver in the case of Nolvadex).

SERMs do not lower circulating levels of estrogen in the plasma.

Aromatase inhibitors do this by eliminating estrogen production by binding to and neutralizing the aromatase enzyme, which is the enzyme that converts (or aromatizes) androgens into estrogen.

Letrozole is a non-steroidal, non-lethal aromatase inhibitor and belongs to the third-generation aromatase inhibitor class.

Letrozole is very similar to Arimidex and is one of the three major aromatase inhibitors (Arimidex, Aromasin, and Letrozole).

The difference between letrozole and the other two major aromatase inhibitors is the fact that while it is used to treat postmenopausal female breast cancer patients, it is actually specifically used for estrogen receptor unknown breast cancer.

This is a condition of breast cancer where the diagnosis does not tell if estrogen is the cause or if the breast cancer has been made worse by estrogen.

Like all other aromatase inhibitors, letrozole is typically used after first-line treatments (such as Nolvadex) have failed, but in rare cases, letrozole may need to be used as a first-line treatment for a variety of conditions.

Letrozole was developed after Arimidex but before aromasin, and is the most potent and effective of the aromatase inhibitors.

Novartis manufactured the drug after it was approved for sale in the U.S. prescription drug market in 1997, and it is sold in some countries around the world, primarily in parts of Europe, under the brand name Femara and a separate brand name, Pema.

Like other aromatase inhibitors, it has become very widespread and common in North America, as well as in regions, countries, and markets around the world, with more than 70 countries carrying Letrozole, and the brand name Femara is estimated to be the most popular and most widely used.

In addition to the main brand name, letrozole is also sold under numerous other generic brands.

Letrozole (Femara), like all aromatase inhibitors, has become popular among athletes, bodybuilders, and people who use anabolic steroids naturally.

This is due to Letrozole's ability to modulate and reduce estrogen, making it a favorite among anabolic steroid users who use anabolic steroids (such as testosterone, Dianabol, Equipoise, etc.), as well as its ability to effectively control the problems caused by too much estrogen (abdominal bloating, blood pressure, gynecomastia, etc.).

Chemical Properties of Letrozole

Letrozole (Femara) is a non-steroidal aromatase inhibitor.

This means that unlike aromasin (Exemestane), which is a steroidal aromatase inhibitor, it does not have the characteristic 4-membered cycloalkane ring carbon structure common to all classes of steroids.

Properties of Letrozole

Studies have shown that letrozole's effectiveness in controlling serum estrogen levels is the strongest and most effective of the three major aromatase inhibitors.[1][2] Letrozole is the most potent and effective of the three major aromatase inhibitors.

The information pamphlet included with the medication also states that the standard tablet dose of 2.5 mg is effective in reducing blood estrogen levels by an average of 78%.

However, actual clinical data has demonstrated a much more effective reduction (remember, 78% is a determined average).

Studies have shown that letrozole reduces serum estrogen levels by at least 98% [2].

Because letrozole is so effective at lowering estrogen levels by inhibiting the aromatase enzyme, it is typically only given to postmenopausal women or used when other first-line treatments for breast cancer have failed.

This is a common aspect of their use, as all three major aromatase inhibitors are highly effective compounds at reducing estrogen, with letrozole being the most effective.

Both Arimidex and Letrozole are classified as non-steroidal and non-lethal aromatase inhibitors that compete with the substrate for binding to the enzyme's active site.

This is very different from aromasin (exemestane), which is a steroidal and suicidal aromatase inhibitor based on a mechanism that mimics the substrate and is converted by the enzyme into a reactive intermediate that inactivates the aromatase enzyme [3].

In layman's terms, this means that aromasin's chemical structure is similar to the traditional 'targets' that aromatase binds to (e.g. testosterone) and essentially 'tricks' the aromatase enzyme into binding to inhibit/inactivate it.

Because the binding strength is so strong, this inhibition of the aromatase enzyme that aromasin binds to is permanent.

Arimidex and letrozole are non-lethal aromatase inhibitors, so they compete with the traditional 'target' of the enzyme rather than taking up a permanent position (which is an advantage aromasin has over the other two).

Letrozole, like all aromatase inhibitors, has also demonstrated the ability to increase the endogenous production of LH (luteinizing hormone), FSH (follicle stimulating hormone), and consequently testosterone levels in men, but this will be covered in more detail in the Letrozole Dosage section of the profile.

Bodybuilders and athletes who use anabolic steroids typically favor aromatase inhibitors such as Letrozole because they can eliminate aromatase, which is the root cause of elevated estrogen levels.

Neutralizing the aromatase enzyme prevents physiologic levels of aromatized androgens such as testosterone, Dianabol, and Deca Durabolin from being converted to estrogen, eliminating the risk of estrogen-related side effects.

Letrozole side effects

If you're curious about the possible side effects of letrozole, this detailed guide will help.

Letrozole belongs to a class of medications called aromatase inhibitors.

The side effects are similar to those of another popular aromatase inhibitor (AI) known as Arimidex.

Weakness and fatigue are the two main side effects most often experienced by letrozole users.

The drug is used to treat infertility.

It is also popular among bodybuilders and those who use anabolic steroids to build muscle.

Letrozole has the ability to reduce certain side effects associated with anabolic steroids.

For example, men who want to avoid feminizing side effects such as gynecomastia may find this drug to be effective.

The drug suppresses the production of estrogen, which helps prevent feminization problems in steroid users.

Anabolic steroid users who use letrozole also tend to avoid letrozole side effects if the estrogen suppression is not too severe.

However, there are exceptions.

For example, bodybuilders who undergo intense preparation before a competition may train intensely while maintaining a strict diet.

These types of bodybuilders may be more susceptible to letrozole side effects.

Because strict diets and hard training tend to cause fatigue and weakness, it can sometimes be difficult for bodybuilders to know if side effects are due to letrozole, their current lifestyle, or both.

Other possible side effects associated with this medication include hot flashes, headache, depression, joint pain, and headache.

In addition, this medication sometimes reduces the mineral content inside the bones.

This can put letrozole users at an increased risk of developing osteoporosis.

However, since many steroids increase the mineral content inside the bones, anabolic steroid users who use letrozole in combination tend to have a lower risk.

One anabolic steroid that increases the mineral content of bone is nandrolone.

Some people have a negative reaction to letrozole, while others do not.

Everyone's body is different and their response to the drug is individualized.

Keep this in mind when deciding whether or not to use letrozole.

If you take the drug and don't react well to it, you should know that there are other medications that serve the same purpose.

The alternative medication may be better tolerated by your body.

The last side effect associated with letrozole is cholesterol problems.

Specifically, HDL cholesterol levels can decrease due to the use of the drug.

When used alone, this AI drug does not seem to have a statistically significant effect.

However, when used in combination with anabolic steroids, it can cause cholesterol problems.

Many anabolic steroids can have a negative effect on cholesterol levels.

When used in combination with anabolic steroids, there is a risk of worsening cholesterol problems.

Statistics from clinical studies show that therapeutic doses of testosterone have few negative effects.

However, when testosterone and letrozole are used together, the combination of the two drugs can suppress HDL cholesterol levels by up to a quarter.

This is a fairly significant suppression and should be taken with caution.

If testosterone is administered at “supraphysiologic” levels, minimal HDL inhibition can be expected.

If the same dose is used in combination with an aromatase inhibitor, HDL inhibition of 20% (or more) can be expected.

Due to the risk of cholesterol-related side effects, especially when anabolic steroids are used in combination, it is important that individuals taking Letrozole maintain a lifestyle that promotes healthy cholesterol levels.

For example, choosing a diet that minimizes saturated fat and simple sugars can be helpful.

It is also helpful to add more omega fatty acids to your daily diet.

You can get omega-3 fatty acids from supplements or through your diet.

Taking a supplement may be a more convenient way to get the amount you need.

Some people taking letrozole also find it beneficial to take a cholesterol antioxidant supplement.

Also, if you plan to use letrozole or are already using it, add aerobic exercise to your lifestyle.

Because of the risk of cholesterol issues, some anabolic steroid users prefer to take SERMs to counteract estrogenic side effects.

SERMs don't always solve all problems, but they do work for many people.

If you need an aromatase inhibitor, taking about 10 milligrams of Nolvadex daily with an AI may be enough to maintain optimal cholesterol levels.

SERMs promote normal cholesterol levels.

Letrozole dosing and uses

Most women who are prescribed letrozole to treat breast cancer take 2.5 milligrams per day.

This dose is very strong and is usually taken until breast cancer symptoms disappear.

When breast cancer patients enter remission, they are switched from letrozole to Nolvadex to prevent a recurrence of the same disease.

At this dose level, the potential for weakness and fatigue is quite high.

Anabolic steroid users typically take low doses, such as half to one milligram of the drug per day.

Men who experience “man boobs” (gynecomastia) associated with anabolic steroid use sometimes take higher doses, such as 2.5 milligrams per day.

However, taking such high doses increases the risk of side effects.

This medication is sold under the brand name Femara.

Femara is available worldwide in a convenient tablet form.

You need a prescription to buy it.

However, the black market allows research chemical laboratories to sell letrozole, and anabolic steroid suppliers (underlab) may also sell it.

There are many aromatase inhibitors on the market, the most popular and well-known of which is Arimidex.

That said, many people prefer letrozole, and sometimes people experiment with both at different times to find what works best for them.