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Beta-blocker drugs


beta-blocker-drugs

Beta-blockers of receptors are the drugs which have an antagonistic effect on beta adrenergic receptors. Their most effects are on the cardiovascular system and smooth bronchial muscles. They block the effect of adrenaline and noradrenaline on beta adrenergic receptors in a body (in the heart, periphery blood vessels, bronchies and liver).

They are used at a great number of diseases – arrhythmia, stenocardia, congestive heart insufficience, hypertension, the prevention of the heart infarct. Besides, they are used for the treatments of glaucoma, gullet, tension, for migraine prevention. This is the main reason for regarding them as the most important drug groups.

There are three kinds of beta adrenergic receptors: beta-1 receptors in the heart, beta-2 receptors in the lungs, muscles and arterioles and in the whole body.  Beta-3 receptors are less expressed, but they have the function in the metabolism of oils. Activation of beta 1-receptors by adrenaline increase the heart function and blood pressure using more oxygen.  Drugs which block these receptors have the opposite effect – they decelerate the heart function and lower the blood pressure so they are used in cases when oxygen cannot reach the heart. Beta-2 receptors are situated in the blood vessels of smooth muscles, striated muscles, and the smooth muscle of digestive organs, the uterus, and the liver. By activation of these receptors, the blood vessels are widened in the skeletal muscles, the bronchies are also widened, the uterus is slackened, and the digestive organs dissolve glycogen in the liver and discharging of glucose in blood from the liver.  On the other hand, the blockage of beta-2 receptors manifests the opposite effects.

Beta blockers are differentiated according to their ability to blockade beta-1 or beta-2 receptors. If they blockade the other group of receptors, they are called nonselective beta blockers. Such blockers have a wide spectrum of functioning on numerous organs and the system of organs, but they also have the side effects. Selective beta blockers blockade only beta-1 receptors in great dosages by blockading other beta receptors.

The special group of beta blockers is also the beta blockers which are alpha blockers at the same time. They are labetalol and carvedilol. They are very suitable for rapid control of blood pressure as the additional blockade of alpha-receptors and prevent the characteristic blood pressure increasing which manifests if beta-1 blockers are blockaded.

After a long treatment by beta blockers as an answer to the blockade of the sympatic system the number of beta receptors is increased. The sudden interruption of beta blockers can cause so-called "rebound effect", the risk of stenocardia or infarct manifestation.  

The side effects of beta blockers are bronchospasam, the reduced heart contractility, bradychardia, hypotonic cardiovascular dysregulation, the dysfunction of blood circulation, the increased hypoglycemia in the patients with diabetes melitus.

Propranolol

Propranolol is nonselective inhibitor of beta-adrenergic receptors. Its most important effect is the heart protection from the excitement or circulating catecholamines of the physical and psychic causes.  Propranolol decreases the heart frequency and the heart contractions. It also reduces the minute volume and the need of the heart muscle for oxygen. It also has a local and an anaesthetic effect.

It is applied in the treatments of stenocardia, arrhythmia, hypertension, hypertrophic obstructive cardiomyopathy, phaeochromocytoma.

The most frequent side effects are bradycardia, the heart decompensation, atrioventricular block, hypotension Raynaudov phenomenon and paraesthesia; bronchospasm and the deterioration of ventilation functions, inclination towards hypoglycaemia especially at diabetes, nausea, vomiting, constipation, mental depression, insomnia, hallucinations, fatigue, purpura and erythema.  Propranolol is widely used due to its ability to go through the barriers and enter the brain where it causes many side effects such as depression and nightmares.  Sotalol is nonselective beta-blockers which prolongs the duration of active potential blocking repolarisation entering of calium ions in the cells of the heart muscle.  

Sotalol

Sotalol is used in treatments of tachycardia of AV knot, supraventricular tachycardia in WPW syndrome, paroxysmal fibrillations of the atrium, difficult symptomatic, malignant and nonmalignant tachycardiac ventricular the heart rhythm dysfunctions, hypertensions and coronary heart diseases united with the dysfunctions of the heart rhythm.  

The possible side effects are fatigue, virtiligo, weakness, headaches and the feeling of coldness in extremities.

Atenolol

Atenolol is the most important and most prescribed beta blocker. It selectively blocks beta-1 adrenergic receptors. Atenolol reduces, during the state of sleep or physical work, the main volume, the frequence of heart function, the systolic blood pressure and the need of the myocardium for oxygen which enables the greater heart function.   

But it also reduces the strength of the heart muscle which is the negative effect at patients who suffer from the congestive insufficience of the heart.

Atenolol is most frequently used in the treatments of hypertension, and for the long-standing treatments of stenocardia or tachyarrhythmia.  

The possible side effects are bradychardia, congestive insufficience of the heart and the coldness of extremities, orthostatic hypotension, arrhythmia, bronchospasm, reduced sexual abilities, insomnia, the sleep problems, fatigue or weakness, tension and nasal congestion. Other side effects are: constipation, diarrhea, nausea, vomiting.

Karvedilol

Karvedilol is the beta blocker which possesses the characteristics of vasodilator – it ligates for alpha-1 receptors and blocks them causing the widening of blood vessels. Besides, karvedilol is a power antioxidant that is a neutralizator of reactive free radicals and antiproliferative agens.  

Karvedilol reduces the periphery vascular resistance by vasodilation and blockage of renine-angiotenzin-aldosteron system. (Due to beta blockers).

At patients with high blood pressure, it lowers the blood pressure, and the heart velocity is reduced. The blood circulation through the kidneys and kidney function is preserved. The blood circulation is also possible through the extremities; the manifestation of cold extremities which is possible at the use of other beta blockers, at the use of karvedilol is rare.
Karvedilol is used for the treatments of hypertension, in combination with other antihypertensive drugs, especially with diuretics such as tiazide, or in the treatments of stenocardia, the ischemia of the heart muscle, unstable stenocardia and ischaemic dysfunction of the left chamber.  Karvedilol is used in the treatments of congestive insufficience of the heart and leads to the death reduction and need for hospitalization, the improvement of the states and deceleration of the diseases.  It can be used as an addition to the standardized therapy which does not include ACE inhibitor, or at patients who are not on the therapy with digitalis, hydralazine or nitrate.

The possible side effects are the eye sight dysfunction, headaches and fatigue, bradycardia, postural hypotension, edema, nausea, hypercholesterolaemia, vomiting, diarrhea, the increasing of the body weight, astma, the pain in extremities, and the reduced lacrimation.

The registered drugs

  • propranolol – PROPRANOLOL (Galenika Serbia),
  • sotalol – DAROB MITE (Abbott Germany),
  • metoprolol – CORVITOL (Berlin-Chemie Germany), METOPROLO STADA (Stada Arzneimittel Germany), PRESOLOL (Hemofarm Serbia),
  • atenolol – ATENOLOL (Farmakos Serbia),  ATENOLOL (Remevita Serbia),  ATENOLOL (Zdravlje Serbia),  PANAPRES (Hemofarm Serbia), PRINORM (Galenika Serbia),
  • bisoprolol – BISOPROLOL (Jugoremedija Serbia), BISOPROLOL (Ni Medic Serbia), BYOL (The Drug of Farmaceutical Industry of Slovenia), CONCOR (Merck Germany), CONCOR COR (Merck Germany),
  • nebivolol – NEBOLET (Berlin-Chemie Germany),
  • karvedilol – KARVEDILOL (Habit Pharm Serbia), KARVILEKS (Zdravlje Serbia), MILENOL (Hemofarm Serbia), CORYOL (Krka Slovenia), DILATREND (F.Hoffmann-La Roche Switzerland),
  • bisoprolol, hydrochlortiazid – LODOZ (Merck Sante France).


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