The effect of drugs on the body

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The originality of absorption of drugs from the rectum , and the mouth is that they are not exposed to the gastro-intestinal juice and enter the bloodstream, partially bypassing the liver. This allows you to use the following ways of introduction in the appointment of any drugs that are rapidly inactivated in the liver (for example, tablets hypertension acetate it is therefore necessary to keep the language until resorption).
The drug received in the blood associated with the plasma protein or circulates freely. The associated form is a kind of depot of the drug in the blood. Free same form pharmacologically active, and therefore the factors causing rapid transition bound form in a free, can lead to intoxication. Most often this occurs in combination therapy. For example, bleeding that occurs when appointing butadiona patients receiving anticoagulants, because this drug releases from the connection with plasma proteins large number of anticoagulants, the coagulation of blood is dramatically reduced. The same mechanism is the basis of jaundice caused by the admission of sulfonamides.
The distribution of freely circulating medicinal substances between individual organs and tissues depends mainly on the nature of the drug and especially from the blood. So, first of all the drug reaches the organs and tissues with good vascularization (liver, lungs, kidneys, heart, brain).
Tissue barriers (the blood-brain, placental and others) prevent the penetration of the drug in tissue. Of particular interest is the placental barrier, protecting the fetus from exposure to drugs and other toxic substances circulating in the mother's blood. However, some substances overcome this barrier and can have embryotoxic effect (for example, alcohol, morphine, nicotine).
The level of concentration of the drug in the body depends essentially on biotransformation, or metabolism of drugs. Most of them undergo either partial or almost total transformation. Only individual compounds are excreted in unchanged form. Ways and means biotransformation mainly known. In the body there is a biochemical system or organ intended only for the metabolism, as this process occurs in all tissues, with a corresponding set of enzymes.
Especially numerous enzymes in the liver, where they are predominantly localized in microsomes. Considering the large size of the liver, rich vascularization, it becomes clear why it is the main body responsible for the fate of drugs in the body. But this does not diminish the importance of enzymes kidneys, lungs, intestines and blood plasma in biotransformation.
Transformation of medicinal substances essentially change under the influence of age, gender, diet, alcohol, Smoking, various pathological conditions, as well as environmental factors.
An important role in the individual patient response to medications, in the biotransformation of substances play a genetically determined features of the activity of enzyme systems. An example would be prolonged apnea caused by the introduction ditilina. We are talking about congenital anomalies of psevdoholinesterzy, which is not able to hydrolyze ditilin with normal speed.
The transformation of drugs in children also occurs primarily in the liver. By the time of birth in the liver can oxidize many chemical compounds. However, the activity of a number of enzyme systems involved in the biotransformation in this period remains low, which explains the increased sensitivity of children to many drugs.