Xenical - a powerful, specific and reversible inhibitor of gastrointestinal lipases, which has a long-lasting effect. Its therapeutic effect is carried out in the lumen of the stomach and small intestine and consists in the formation of a covalent bond with the active serine portion of the gastric and pancreatic lipases. The inactivated enzyme at the same time loses the ability to break down food fats coming in the form of triglycerides, to sucking free fatty acids and monoglycerides. Since uncleaved triglycerides are not absorbed, the resulting decrease in the intake of calories into the body leads to a decrease in body weight. Thus, the therapeutic effect of the drug is carried out without absorption into the systemic circulation.