Alpha-blockers are large andheterogeneous group of drugs. In the seventies, interest in these medicines decreased significantly due to the fact that specialists began to use thiazide diuretics, ACE inhibitors to treat hypertension. By the beginning of the nineties, it was found that alpha 1-blockers selective prolonged exposure (mainly, the drug "Doxazosin") are comparable in terms of tolerability, safety, antihypertensive activity with other drugs, whose action is aimed at lowering blood pressure. In addition, the medicines have been found and additional properties that allow to assign them to patients with diabetes mellitus, benign prostatic hyperplasia, dyslipidemia, disorders in the sexual sphere of men, and obliterating endoarteritis.
Alpha-adrenoblockers. Classification
The drugs are divided into two main categories: selective and nonselective.
The group of nonselective agents includes alpha 1- and 2-adrenoblockers (for example, the drug "Fetolamine").
To selective include such medicines as"Terazozin", "Doxazosin", "Prazozin". Drugs of this category predominantly affect the receptors, which are located in the smooth muscles of the prostate, the neck of the bladder, as well as the prostatic site of the urethra.
Some antihypertensive drugs,related to other groups of agents, exhibit the same properties as alpha-blockers. These drugs, in particular, include the drug "Carvedilol".
There are also drugs whose properties are similarin that they display both beta and alpha-blockers. Such medicines, in addition, have antioxidant properties. The mechanism of their effect is to compete with catecholamines. The fight is carried out for peripheral adrenergic receptors alpha 1 and beta-adrenergic receptors. With prolonged use, the effect of these medicines begins to subside, and after a few months disappears altogether.
Alpha-adrenoblockers have a largenumber of advantages. In particular, they have a beneficial effect on the level of triglycerides and cholesterol in the blood plasma. This significantly reduces the risk of atherosclerosis. The drugs do not affect the concentration in the blood of sugar, lower the pressure, without increasing the frequency of contraction of the heart. In addition, these drugs do not affect the state of potency.
Adverse effects in alpha-blockers are quite small. The most significant is the "effect of the first reception."
It should be said that alpha-blockersthere is the ability to expand both small, and large enough blood vessels. In this regard, the reduction in pressure is most clearly manifested in the vertical position of the patient, and less clearly in the horizontal position. When a person (normally) rises from the bed, the nervous system strengthens the arterial tone. This is necessary to adapt the body to a vertical position. Reception of alpha 1-adrenoblockers interferes with this device. When a person assumes a vertical position, the pressure drops sharply. As a result, the brain receives oxygen in insufficient quantities. The person begins to darken in the eyes, dizzy, there may come a sharp weakness, in some cases the patient may faint. After falling into a faint (assuming a horizontal position), the blood supply to the brain is improved. As a result, consciousness soon returns to the patient. Such a faint, in fact, does not in itself carry a great danger. However, during the fall, it is likely that the patient can get a dangerous injury.
