Use Of β-Blockers

Use Of β-Blockers

Write Briefly On β Receptor Blocker.
Or
Describe Briefly β (Beta)­Blockers And Their Indications.
Or
Enumerate Important Indications, Contraindications, and Adverse Reactions of β Blockers.
Or
Write A Short Answer On Contraindications To Use Of β-blockers.
Answer:

These drugs inhibit responses mediated by the adrenergic β blockers.

Use of β-Blockers: Mechanism, Indications, and Side Effects

β Receptor Blocker Classifiation

• Cardioselective (β1): Metoprolol, atenolol, acebutolol.
• β2 selective: Butoxamine.
• Nonselective (β1+β2): Propranolol, nadolol, sotalol, timolol.

β-Blockers in Hypertension: Treatment and Dosage

β Receptor Blocker Actions

• Heart: These drugs decrease the force of contraction, decrease AV conduction, decreases heart rate, and decrease automaticity of myocardial fibers thus cardiac output is decreased.
• Blood vessels: On prolonged administration BP falls in hypertensives.
• Respiratory system: It causes an increase in bronchoconstriction in asthmatics.
• Eye: β-blockers decrease aqueous humor secretion.

Adverse Effects And Contraindications

Adverse Reactions

• CVS: Bradycardia, heart block, and can precipitate heart failure.
• Respiratory system: These drugs can precipitate bronchial asthma.
• CNS: Disturbed sleep, fatigue, hallucination, and mental depression.
• Muscular weakness and tiredness.
• Abrupt withdrawal can cause angina or frank myocardial infarction.

Contraindications

• They are contraindicated in asthmatics and COPD.
• They are contraindicated in patients of print metal angina.
• They are contraindicated in peripheral vascular disease.
• They are contraindicated in patients with low cardiac reserve.
• They are contraindicated in diabetics who are taking oral antidiabetic drugs as they delay recovery from hypoglycemia.

β-Blockers for Heart Disease: Clinical Uses and Benefits

Uses Or Indications Of β Blockers

• Hypertension: β blockers are used to treat all grades of hypertension. They are also indicated in angina, myocardial infarction, and cardiac arrhythmias.
• In the prophylaxis of angina and myocardial infarction: β blockers decrease the oxygen demand of the myocardium and decrease the heart rate. These drugs reduce the frequency of angina attacks. They are indicated in the acute phase of myocardial infarction so that they limit the size of the infarct.
• In cardiac arrhythmias: They are indicated in atrial arrhythmias, i.e. atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia.
• Congestive cardiac failure: Chronic usage of β blockers reduces the rate of mortality during chronic heart failure.
• Pheochromocytoma: These drugs control cardiac manifestations produced by pheochromocytoma.
• Glaucoma: They decrease intraocular pressure by decreasing the secretion of aqueous humor. Timolol is the choice of drug.
• In the prophylaxis of migraine: They decrease the frequency of migraine headaches.
• Hyperthyroidism: Signs and symptoms of hyperthyroidism decrease due to the blockade of β receptors.
• Essential tremors: Propranolol provides relief in tremors.
• Anxiety: It acts as an anti-anxiety drug.
• Alcohol withdrawal: Propranolol provides benefits for alcohol withdrawal.
• Dissecting aortic aneurysm: β blockers reduce cardiac contractility as well as the development of pressure during systole.