Clenbuterol hydrochloride is an anti-asthma medication that belongs to a broad group of drugs knows as sympathomimetics. These drugs affect that sympathetic nervous system in a wide number of ways, largely mediated by the distribution of adrenoceptors. There are actually nine different types of these receptors in the body, which are classified as either alpha or beta and further subcategorized by type number. Depending on the specific affinities of these agents for the various receptors, they can potentially be used in the treatment of conditions such as asthma, hypertension, cardiovascular shock, arrhythmias, migraine headaches, and anaphylactic shock. The text Goodman and Gillman’s The Pharmacological Basis of Therapeutics 9th edition does a good job of describing the diverse nature in which these drugs affect the body

How to use : When used for the management of asthma, the most common clinical dose for adults is 20 mcg (1 tablet) twice per day. Some patients require up to 40 mcg (2 tablets) twice per day. When using the drug (off-label) for physique- or performance-enhancing purposes, bodybuilders and athletes generally tailor their dosage and cycling of this product based on personal sensitivity to its benefits and side effects. To accomplish this, one often begins a cycle by taking one or two tablets per day, and gradually increasing the dosage every third day by one half to 1 tablet until a desired dosage range is established. At peak therapy some users can tolerate as many as 6-8 tablets per day (120-160 mcg). Given the potency and potential for serious side effects, however, any dosage outside of the normal therapeutic range should be approached with an even greater level of caution.