Most ofthe actions of catecho/amines and sympathomimetic agents can be classified in to seven broad types: (1) peripheral excitatory action on certain types of smooth muscles such as those in blood vessels supplying the skin, kidney and mucous membranes, and on the gland cells, such as those of the salivary and sweat glands; (2) a peripheral inhibitory action on certain other types of smooth muscle, such as those in the wall of the gut; in the bronchial tree, and in blood vessels supplying skeletal muscle; (3) a cardiac excitatory action, responsible for an increase in heart rate and force of contraction; (4) metabolic actions, such as an increase in the rate of glycogenolysis in liver and muscle and liberation of free fatty acids from adipose tissue; (5) endocrine actions, such. as modulation of the secretion of insulin, rennin, and fggltffy hormones; (6) CNS actions, such as respiratory stimulation and, with some of the drugs, an increase in wakefulness and psychomotor activity and a reduction in appetite; and (7) presynaptic actions that result in either inhibition or facilitation of the release of the neurotransmitters such as such as norepinephrine and acetylcholine. Clenbuterol hydrochloride is specifically a selective beta-2 sympathomimetic, primarily affecting only one of the three subsets of beta-receptors. Of particular interest is the fact that this drug has little beta-1 stimulating activity. Since beta-1 receptors are closely tied to the cardiac effects of these agents, this allows clenbuterol hydrochloride to reduce reversible airway obstruction (an effect of beta-2 stimulation) with much less cardiovascular side effects compared to non—se|ective beta agonists. Clinical studies with this drug show it is extremely effective as a bronchodilator, with a low level of user complaints and high patient compliance. Clenbuterol hydrochloride also exhibits an extremely long half-life in the body, which is measured to be approximately 34 hours long .This makes Steady blood levels easy to achieve, requiring only a single or twice daily dosing schedule at most. This of course makes it much easier for the patient to use, and may tie in to its high compliance rate. In animal studies clenbuterol hydrochloride is shown to exhibit anabolic activity , obviously an attractive trait to a bodybuilder or athlete. This compound is additional a known thermogenic, with beta-2 agonists like clenbuterol hydrochloride shown to directly stimulate fat cells and accelerate the breakdown of triglycerides to form free fatty acids. lts efficacy in this area makes clenbuterol hydrochloride a very popular fat loss drug among the bodybuilding community.Those interested in this drug are often hoping it will produce a little of both benefits promoting the loss of body fat while imparting increases in strength and muscle mass. But as was well pointed out by a review published in the August 1995 issue of Medicine and Science in Sports and Exercise, the possible anabolic results in humans are very questionab|e,and based only on animal data using much larger doses than would be required for bronchodilation .With such reports there has been a lot of debate as to whether or not clenbuterol hydrochloride is really anabolic in humans at all. some seem to swear by the fact that it builds muscle, and use clenbuterol hydrochloride regularly as an off-season or adjunct anabolic. To others, the MSSE report is confirmation that athletes have wasted valuable time and money on drugs that do not build muscle.The debate over clenbuterol hydrochloride’s potential anabolic activity continues today.