Introduction : Beta-blockers, also known as beta antagonists, beta-adrenergic blocking agents, or beta-adrenergic antagonists, are drugs that are prescribed to treat several different types of conditions, including hypertension (high blood pressure), angina, some abnormal heart rhythms, heart attack (myocardial infarction), anxiety, migraine, glaucoma, and overactive thyroid symptoms. Beta-blockers block the action of the sympathetic nervous system of the heart, thus reducing stress on the heart. The sympathetic nervous system activates the “fight or flight” response. It is part of the autonomic nervous system.
Beta-blockers block beta-adrenergic substances, such as apinephrine (adrenaline) in the autonomic nervous system (involuntary nervous system). They slow down the heart beat, decrease the force of the contractions of the heart muscles, and reduce blood vessel contraction in the heart, brain, as well as the rest of the body. Generic Names:| Carvedilol / Metoprolol / Atenolol / Bisprolol / Propranolol / Timolol| Brand Names:| Coreg / Lopressor, Toprol XL / Tenormin / Zebeta / Inderal / Blocadren| How it is given:| Oral (tablet or capsule), intravenous (IV)| Indications :
Doctors may prescribe beta-blockers for patients with tachycardias (rapid heart rates). They help patients with angina by lowering the amount of oxygen the heart muscles require. Angina pectoris occurs when the heart requires more oxygen than it is getting. Beta-blockers can help hypertensive patients because their effects on blood vessels lower blood pressure. Patients with hereditary tremors as well as those who suffer from migraines may benefit from taking beta-blockers. In other words, beta-blockers are known as beta- adrenoreceptor blocking agents and are used to treat: Commonly * Angina * Heart failure.
* High blood pressure (hypertension) * Irregular heart beat (atrial fibrillation) * Myocardial infarction (heart attack) less commonly * Prevention of migraine * Thyrotoxicosis (overactive thyroid) * Anxiety * Tremor * Glaucoma (as eye drops) ————————————————- The first clinically useful beta adrenergic receptor antagonist was called Propranolol. It was invented by Sir James W. Black (born 1924), a Scottish doctor and pharmacologist. Sir James also synthesized Cimetidine (for the treatment of heartburn and peptic ulcers) and was awarded the Nobel Prize for Medicine in 1988.
Propranolol revolutionized the medical management of angina pectoris – it is considered as one of the major contributions to clinical medicine and pharmacology of the 20th century. Mechanism of work : The use of beta blockers in heart failure is primarily associated with the medication’s effect on heart rate. The medication, by way of the sympathetic nervous system, decreases the patient’s heart rate, preventing the heart from having to work harder because of the condition. This effect was not considered desirable for heart failure patients when the medication was first studied, however.
A lowered heart rate has the risk of worsening heart failure symptoms, but as research continued, beta blockers proved to have benefits that outweighed this risk. The exact etiology of the case of heart failure is of importance when a doctor is deciding whether to use beta blockers. A case that is present because of impaired ventricular filling, in contrast to a case caused by impaired ventricular emptying, seems to respond better to beta blockers in heart failure. In addition to their sympathetic action on heart muscle, beta blockers in heart failure influence the kidney’s renin/angiotensin system.
Beta blocking medications cause the secretion of the hormone, renin, to decrease. As renin decreases, a cascade of events transpires that decrease the heart’s demand for oxygen. The cascade lowers extracellular fluid volume and increases the blood’s ability to hold and carry oxygen to body tissues. Beta blocker treatment can be supplemented, and is supplemented in most cases, with diuretics and angiotensin-converting enzyme (ACE) inhibitors that enhance this effect. Patients who have significant dyspnea — shortness of breath — while they remain at rest are among those who may not be candidates for treatment with beta blockers.
Having severe dyspnea can increase the risks that are associated with beta blocker treatment. Some patients are considered hemodynamically unstable if their blood does not carry oxygen well, even under normal circumstances; these patients may not be good candidates for treatment either. Heart problems – for a patient with heart problems beta-blockers can reduce the workload for the heart; so that it does not have to work so hard to supply all parts of the body with oxygen-rich blood. For people with angina, heart failure, or after a heart attack, reducing the heart’s workload is crucial.
Drugs Used in case of Heart Failure : * Propranolol * Metoprolol tartrate (Lopressor) and metoprolol succinate (Toprol XL)| * | * Carvedilol (Coreg)| * | * Bucindolol (Bextra)| * | * Bisoprolol (Zebeta)| * | Side Effects : The most common side effects are: * Cold feet * Cold hands * Diarrhea * Fatigue * Nausea * Very slow heartbeat The following less common side effects are also possible: * Sleeping difficulties and disturbances * Bad dreams (nightmares) * Erectile dysfunction (male inability to achieve or sustain an erection during sex) References : Myo clinic www. Hearthealthywomen. com http://www. wisegeek. com.