Vasodilators are medicines that have a muscle relaxant effect on the walls of the vessels, as a result of which the lumen of the vessels expands. This group of drugs is used mainly as an antihypertensive and analgesic( relieves spasm) therapy.
Vasodilator drugs can be conditionally divided into beta-blockers, nitrates and inhibitors of ACE receptors.
The mechanism of action of B-adrenoblockers is reduced to the closure of the peripheral receptors of the cardiac muscle from the action of catecholamines. They also have the effect of reducing the number of cardiac contractions per minute, resulting in a decrease in cardiac output. Blockade of peripheral receptors leads to a decrease in myocardial oxygen consumption and a decrease in blood pressure.
Beta-blockers have antiarrhythmic effect, and also inhibit renin activity in blood plasma. This group of drugs also has a cardioprotective effect, i.e.contributes to the recovery of myocadiocytes. Beta-adrenoblockers are divided into selective a
- Propranolol and Nadolol( without intrinsic sympathomimetic activity).
- Pindolol and Oxprenolol( with internal activity).
- Bisoprolol, Betoxolol, Atenolol( selective).
There are a number of diseases in which the use of beta-blockers is indicated:
- IHD, angina pectoris;
- arterial hypertension, crisis;
- rhythm disturbance( tachycardia);
- heart failure;
- MI in history;
- a migraine.
There are certain nuances in the appointment of beta-adrenoblockers in pregnancy, diabetes and lactation, but this does not mean that they are contraindicated in these conditions. Absolute contraindications to the prescription of these drugs are:
- chronic obstructive pulmonary pathology;
- peripheral vascular disease;
- heart block of 2-3 degrees.
Side effects with the appointment of blockers:
- vascular disorders in the form of numbness or cold extremities, spasm of large bronchi.
- a violation of the blood formula( increased blood glucose levels, the appearance of urea).
The vasodilator preparations of the nitrate group are one of the earliest drugs that have been used to treat hypertension, myocardial ischemia, crises. The mechanism of their action is to reduce the absorption of oxygen in the myocardium, as a result of which the peripheral veins expand and the venous return of blood decreases. These drugs contribute to increased coronary blood flow due to vasodilation, and, consequently, relieve spasm of the coronary arteries.
Vasoconstrictor drugs of the nitroglycerin series can not be used in the presence of cerebral hemorrhages and increased intracranial pressure.in this situation they only aggravate the severity of the disease.
Vasodilator drugs for the head are used mainly for migraines and spasms of blood vessels. In such situations, it is best to use a group of beta-blockers, they have a pronounced myorelaxing effect on the walls of the vessels.
The last group of drugs is vasodilator drugs that belong to the class of ACE inhibitors. These substances are used mainly with a history of myocardial infarction, hypertension, left ventricular dysfunction of the heart. Contraindications to their appointment are pregnancy, hyperkalemia, stenosis of the renal arteries.
The mechanism of action of these drugs is the manifestation of neurohumoral effects( increased kallikrein-kinin system, increased level of endothelium-relaxing factor) and metabolic effects( antioxidant effect, increased potassium level, increased sensitivity of peripheral tissues).
The drug for vasodilatation is often used in modern medical practice and has a positive therapeutic effect for diseases of the vessels of the head and heart, as well as in the presence of an ischemic process in the cardiac tissue.