Drugs Information Center(DIC)

Effects of beta-adrenergic antagonists may be predicted from the consequences of b receptor stimulation (generally equivalent to the effects of elevated cyclic AMP). Effects of b antagonists at a particular site depend on the level of receptor stimulation, or tone, at that site. Effects of antagonists are more prominent when receptor stimulation by agonist is high. Beta-Adrenergic antagonists may be classified as Non-Subtype Selective (First Generation )-( Nadolol ,Penbutolol ,Pindolol ,Propranolol ,Timolol) Beta 1-Selective (Second Generation ), - ( Acebutolol, Atenolol, Bisoprolol, Esmolol, Metoprolol) and Antagonists with Additional Cardiovascular Actions (Third Generation). Nonselective b blockers with additional actions: Third generation (Carteolol, Carvedilol, Labetalol) Beta1-selective b blockers with additional actions: Third generation (Betaxolol, Celiprolol)

Antagonism of beta-adrenergic receptors affects blood pressure through a number of mechanisms, Reducing cardiac output act on the juxtaglomerular complex to reduce renin secretion and thereby diminish production of circulating angiotensin II. alteration of the control of the sympathetic nervous system at the level of the CNS, altered baroreceptor sensitivity, altered peripheral adrenergic neuron function, and increased prostacyclin biosynthesis. Drugs without intrinsic sympathomimetic activity produce an initial reduction in cardiac output and a reflex-induced rise in peripheral resistance generally with no net change in arterial pressure; peripheral resistance gradually returns to pretreatment values or less. Drugs with intrinsic sympathomimetic activity produce lesser decreases in resting heart rate and cardiac output; the fall in arterial pressure correlates with a fall in vascular resistance below pretreatment levels, possibly because of stimulation of vascular b2 adrenergic recept...

Class of drug: β-Adrenergic receptor blocker. Mechanism of action: Competitive blocker of β adrenergic receptors in heart and blood vessels . Indications/dosage/route : Oral only. Hypertension Adults: Initial: 400 mg/d. Maintenance: 200–1200 mg/d. Premature ventricular contractions Adults: Initial: 200 mg b.i.d. Maintenance: 600–1200 mg/d. Adjustment of dosage • Kidney disease: Creatinine clearance 25–50 mL/min: decrease dose by 50%; creatinine clearance by 75%. • Liver disease: None. • Elderly: Avoid doses >800 mg/d. • Pediatric: Safety and efficacy have not been established in children. Contraindications : Cardiogenic shock, CHF unless it is secondary to tachyarrhythmia treated with a β blocker, sinus bradycardia and AV block greater than first degree, severe COPD. Warnings/precautions Use with caution in patients with the following conditions: diabetes, kidney disease, liver disease, COPD, peripheral vascular disease. Do not stop drug abruptly as this may precipitate arrhy...