Beta-blockers- clinical uses and adverse effects

Beta blockers
Classification
Individual drugs
Uses
Adverse effects

1. Beta-blockers By DR . R SANJAY

2. Mechanism of Action Sympatholytic drugs Beta-blocking drugs occupy beta-receptors, and competitively reduce receptor occupancy by catecholamines and other beta-agonists

3. Types of Beta-blockers Pure Antagonists Binding of these drugs to the beta-receptor does not result in activation of the receptor Partial Agonists They cause partial activation of the receptor, but less than that caused by full agonists like epinephrine and isoproterenol

4. Clinical Uses of Beta-blockers Decrease blood pressure in mild to moderate HTN In severe HTN, prevents reflex tachycardia that results from treatment with direct vasodilators Beta-blockers help reduce mortality after MI Useful in treating effort angina and chronic heart failure Reduce intraocular pressure - especially in glaucoma Useful in treating hyperthyroidism by inhibiting peripheral conversion of thyroxine to T3 Increase stroke volume in patients with obstructive cardiomyopathy

5. Propranolol Nonselective beta-blocker Helps decrease blood pressure by decreasing the cardiac output Inhibits stimulation of renin production by catecholamines; therefore, most useful in patients with high plasma renin Helpful in reducing frequency and intensity of migraines Has a half-life of 3-5 hours Can be administered twice daily Initial dose - 80 mg/day; Maintenance dose - 80-480 mg/day

6. Metoprolol Causes less bronchial constriction compared to propranolol at similar doses Especially useful in treating hypertension in patients with asthma, diabetes, or peripheral vascular disease In patients with chronic heart failure, reduces mortality by preventing cardiac remodeling and decreasing risk of sudden death Has a half-life of 4-6 hours Initial dose - 50-100 mg/day; Maintenance dose - 200-400 mg/day

7. Labetalol Has both beta-blocking and vasodilating effects Reduces blood pressure by reducing systemic vascular resistance without significantly altering heart rate or cardiac output Useful in treatment of hypertension of pheochromocytoma and hypertensive emergencies Oral daily dose - 200-2400 mg/day Dosage for hypertensive emergencies - Repeated IV bolus injection of 20-80 mg

8. Esmolol Beta 1-selective blocker Used for management of intraoperative and postoperative hypertension Helps control severe cardiovascular manifestations of thyroid storm Also useful in controlling supraventricular arrhythmias, and for myocardial ischemia in acutely ill patients Has a short half-life of 10 minutes Loading dose - 0.5-1 mg/kg followed by constant infusion

9. Adverse Effects Bronchoconstriction Bradycardia Arrhythmias Lethargy Disturbances in glucose metabolism Fatigue Insomnia Sexual dysfunction Hypotension

10. Contraindications Asthma and other bronchospastic conditions Severe bradycardia AV Block Bradycardia - tachycardia syndrome Severe unstable left ventricular failure

11. Thank you