Clenbuterol Information

Clenbuterol (AKA Spiropent, Ventipulmin)

Clenbuterol History and Overview

Clenbuterol is not an anabolic steroid, but a stimulant that belongs to a class of compounds known as sympathomimetics.

This class (or 'family') includes other compounds that are more familiar to the general public, such as caffeine, ephedrine, albuterol, amphetamines, and cocaine.

It's actually a very broad category of drugs, and each compound in this family is related to the others, sharing many similarities to some degree and acting in a similar way through similar pathways.

The effects of clenbuterol on the nervous system are related to its interaction with adrenergic receptors located in various tissues and cell types in the body.

When clenbuterol binds to these adrenergic receptors, it produces different effects on different tissue types depending on the tissue being stimulated. One effect of particular concern to us is the effect of clenbuterol on adipose (fat) tissue.

There are two types of adrenergic receptors in the body: alpha receptors and beta receptors, and within these two types there are nine subtypes.

For example, alpha-1, alpha-2, beta-1, beta-2 receptors, and so on.

The difference between clenbuterol and other compounds in the stimulant family is their ability to stimulate different subtypes, multiple subtypes, or focus on one subtype.

In particular, clenbuterol is known to stimulate beta-2 adrenergic receptors very strongly and almost exclusively, which is why clenbuterol is commonly referred to as a beta-2 receptor agonist.

When beta-2 receptors within adipose tissue are stimulated by clenbuterol, lipolysis (the breakdown of fat into free fatty acids) begins.

This is why it is so popular not only among bodybuilders and athletes, but also among celebrities in the entertainment industry and the average person looking to shed a few pounds of fat.

Clenbuterol was originally used in the prescription drug market as a bronchodilator for the treatment of asthma, and is still used today.

It is most often administered in this way in asthma inhalers as the main active drug in the inhaler.

The use of clenbuterol as an asthma treatment is primarily a European medical practice, and in North America, albuterol, a close sister compound of clenbuterol, is used instead.

When beta-2 receptors on the lining of bronchial cells are activated, bronchodilation (opening and dilation of the airways in the lungs, nose, and throat) is initiated.

Almost all sympathomimetics exert this effect, but clenbuterol and albuterol are particularly effective for this purpose.

Clen has also been used medicinally to treat other conditions such as high blood pressure, cardiovascular shock or slowing, cardiac arrhythmias, migraines, allergic reactions and swelling, histamine reactions, and anaphylactic shock.

Clenbuterol is a beta-2 receptor agonist, but it focuses on the beta-2 receptor subtype and also has effects on other receptor subtypes.

In comparison, ephedrine is known to stimulate multiple beta and alpha receptors equally, rather than stimulating one receptor subtype to a greater extent.

Clenbuterol is known in the bodybuilding community for its anabolic effects on muscle tissue.

In fact, clenbuterol has been found to have only minimal anabolic activity in muscle tissue, and this is primarily seen in animals rather than humans (prolonged use is required for these effects to become measurable)[1].

One important thing to note is that with consistent use, clenbuterol stimulates the beta-2 receptors in the body to downregulate them[2], and this happens very quickly.

The sign of this effect is a decrease in fat loss during use until fat loss stops completely.

There are two ways to address this effect.

The first is to stop using the drug (for at least two weeks).

The second is to use ketotifen fumarate, an antihistamine known to upregulate beta-2 receptors [3].

Benadryl has been rumored to have the same effect as ketotifen fumarate on beta-2 receptors, but this has been found to be untrue because while Benadryl is an antihistamine like ketotifen, it works by a very different pathway.

Clenbuterol Side Effects

Clenbuterol is not an anabolic steroid and therefore does not exhibit or cause any of the known side effects associated with anabolic steroid use.

Instead, clen exhibits side effects that are common to all drugs and compounds in the stimulant family.

In other words, many clenbuterol side effects are similar to those of caffeine, ephedrine, and other stimulants, albeit to a different degree.

Clenbuterol side effects also include side effects that are unique to clenbuterol and not found in other stimulants.

The most unique of the clenbuterol side effects is the commonly reported muscle cramping side effect.

This has also been reported as a side effect of clenbuterol's close sibling compound, albuterol.

The reason for this is that clenbuterol depletes taurine in the body.

Studies have shown that clenbuterol use depletes levels of the amino acid taurine in both muscle tissue and serum plasma[4][5].

Taurine, along with magnesium, potassium, and sodium, plays a critical role in the regulation of bioelectrical nerve impulses and signaling that governs contraction and relaxation of all muscle tissue.

When taurine is depleted, intense and painful muscle contractions can occur that are involuntary and often lead to cramps.

Supplementing with 2.5-5 grams of taurine per day has been shown to alleviate these side effects.

As a stimulant, clenbuterol is particularly harsh on heart tissue and the cardiovascular system, but there is some evidence that high doses may promote muscle growth and heart repair in patients with chronic heart failure [6].

However, the maximum clenbuterol dose used in this study is considered extreme and should not be attempted by anyone due to the high risk involved[7].

Myocardial ischemia has also been reported as a risk of clenbuterol use,[8] a condition in which the heart receives an insufficient blood supply due to clenbuterol-induced arterial vasoconstriction.

A study in rats revealed a surprising myotoxic effect of clenbuterol[9], which caused death of the heart muscle and soleus muscle.

The doses used in this study could be considered extreme, however, and are a concern surrounding the use of clenbuterol.

Most of these negative effects associated with clenbuterol and the heart and cardiovascular system are related to cardiac hypertrophy, ventricular hypertrophy, and cardiac necrosis [10].

Undoubtedly, clenbuterol tends to put a great deal of strain on the cardiovascular system, and this is something that all potential users should consider.

Other common clenbuterol side effects include tremors (“hand tremors”), insomnia, sweating and sweating, increased blood pressure and headaches, and nausea.

Clenbuterol side effects may also include side effects such as hives and rashes, or unique allergies and reactions.

Clenbuterol Cycles and Uses

Clenbuterol is most commonly used in cutting, pre-contest, and fat loss cycles.

It is rarely used in the off-season or during bulking phases.

Some clenbuterol users may use clenbuterol during a bulking phase in a (mostly futile) attempt to prevent fat gain during a bulk period when caloric expenditure is much higher than usual and usually higher than basal metabolism.

The truth of the matter here is that the mechanism of clenbuterol does not provide this effect, so those who choose to use it are essentially wasting their time and money.

As previously explained, Clen works by binding to receptors on fat cells and initiating lipolysis, a process in which triglycerides stored in fat cells are released into the bloodstream as free fatty acids.

These released free fatty acids then circulate throughout the body in the bloodstream, where they must undergo fatty acid oxidation, the second step in fat loss.

In other words, the fatty acids must be transported into the cells and mitochondria to be “burned,” and when calorie intake is too high, fatty acid oxidation does not occur properly.

Clenbuterol cycles can be run alone (without other compounds) or stacked with other compounds.

Whether it is run alone or not does not change the way a Clenbuterol cycle is executed.

In other words, clenbuterol is used in a 2 weeks on/2 weeks off protocol (or a steady 8 weeks with ketotifen every 2 weeks).

It is not recommended to use clenbuterol for more than 12 weeks to allow the body's cardiovascular and other systems to get a well-deserved break from the compound.

Clenbuterol Dosage and Administration

As an asthma medication for the treatment of asthma, the dosage of clenbuterol ranges from 20 to 40 mcg per day.

The maximum clenbuterol dose that an individual should ultimately titrate to in order to achieve a significant amount of fat loss should be between 120 and 160 mcg per day.

Women can tolerate lower amounts, ranging from 80 to 100 mcg per day.

Whether the user is male or female, the dosage should be titrated (or 'ramped up') slowly to the mentioned maximum dose.

For example, an initial starting dose of 40 mcg of Clenbuterol for the first three days means that on the fourth day, the user will increase their Clenbuterol dose by another 20 mcg (now totaling 60 mcg per day), increase again after three days, and so on.

Some individuals may be able to tolerate a faster upward titration, while others may need a slower, more steady increase.

It is not necessary to taper down when discontinuing clenbuterol use, but some individuals prefer to do so.

The half-life of clenbuterol is approximately 37 hours, so ideally all clenbuterol doses should be taken together in the morning.

It is not necessary to spread clenbuterol doses throughout the day, and can actually worsen insomnia and sleep disorders.

Clenbuterol Resources

[1].The anabolic action of clenbuterol on skeletal muscle is mediated by beta 2-adrenoceptor activation. Choo JJ, Horan MA, Little RA, Rothwell NJ. Department of Physiological Sciences, Manchester School of Medicine, Manchester, United Kingdom. Am J Physiol. 1992 Jul;263(1 Pt 1):E50-6.

[2].Effects of dietary clenbuterol and simaterol on muscle composition, beta-adrenoceptor and androgen receptor concentrations in broilers. Schiavone A, Tarantola M, Perona G, Pagliasso S, Badino P, Odore R, Cuniberti B, Lussiana C. J Anim Physiol Anim Nutr (Berl). 2004 Apr;88(3-4):94-100.

[3].Effects of ketotifen and clenbuterol on beta-adrenoceptor function on lymphocytes and plasma TXB-2 levels in asthmatic patients. Huszar E, Herjavecz I, Boszormenyi-Nagy G, Slapke J, Schreiber J, Debreczeni LA. Z Erkr Atmungsorgane. 1990;175(3):141-6.

[4].Effects of the beta 2-agonist drug clenbuterol on taurine levels in rat heart and other tissues. Amino Acids. Doheny MH, Waterfield CJ, Timbrell JA. 1998;15(1-2):13-25.

[5].Effects of beta-agonist treatment on tissue and urinary taurine levels in rats. Mechanisms and implications for protection. Waterfield CJ, Carvalho F, Timbrell JA. Adv Exp Med Biol. 1996;403:233-45.

[6].Clenbuterol increases lean muscle mass but not endurance in patients with chronic heart failure. Kamalakkannan G, Petrilli CM, George I, LaManca J, McLaughlin BT, Shane E, Mancini DM, Maybaum S. J Heart Lung Transplant. 2008 Apr;27(4):457-61. doi: 10.1016/j.healun.2008.01.013.

[7].Effects of clenbuterol on cardiac and skeletal muscle function during left ventricular assist device support. George I, Xydas S, Mancini DM, Lamanca J, DiTullio M, Marboe CC, Shane E, Schulman AR, Colley PM, Petrilli CM, Naka Y, Oz MC, Maybaum S. J Heart Lung Transplant. 2006 Sep;25(9):1084-90.

[8].Myocardial ischemia associated with clenbuterol abuse: report of two cases. J Emerg Med. May 24, 2012. Huckins DS, Lemons MF. Department of Emergency Medicine, Newton-Wellesley Hospital, Newton, Massachusetts.

[9].Myotoxic effects of clenbuterol on rat heart and gastrocnemius muscle. Journal of Applied Physiology, February 22, 2002. Jatin G. Burniston, Yeelan Ng, William A. Clark, John Colyer, Lip-Bun Tan, David F. Goldspink.

[10].Chronic clenbuterol administration negatively alters cardiac function. Sleeper MM, Kearns CF, McKeever KH. Med Sci Sports Exerc. 2002 Apr;34(4):643-50.