Metoprolol

Metoprolol is a selective adrenergic beta-1 blocking agent that is commonly used to treat angina pectoris; hypertension; & cardiac arrhythmias.
Metoprolol is a cardioselective 1-adrenergic blocking agent used for acute myocardial infarction (mi), heart failure, angina pectoris & mild to moderate hypertension. It may also be used for supraventricular & tachyarrhythmias and prophylaxis for migraine headaches. metoprolol is structurally similar to bisoprolol, acebutolol and atenolol in that it has two substituents in the para position of the benzene ring.the 1-selectivity of these agents is thought to be due in part to the large substituents in the para position. At low doses, metoprolol selectively blocks cardiac 1-adrenergic receptors with little activity against 2-adrenergic receptors of the lungs & vascular smooth muscle. Receptor selectivity decreases with higher doses. Unlike propranolol & pindolol, metoprolol does not exhibit membrane-stabilizing or intrinsic sympa thomimetic activity. Membrane-stabilizing effects are only observed at doses much higher than those needed for -adrenergic blocking activity. Metoprolol possesses a single chiral centre and is administered as a racemic mixture.