| Indication | For the management of acute myocardial infarction, angina pectoris, heart failure and mild to moderate hypertension. May be used to treat supraventricular and tachyarrhythmias and as prophylaxis for migraine headaches. |
| Pharmacodynamics | Metoprolol, a competitive, beta1-selective (cardioselective) adrenergic antagonist, is similar to atenolol in its moderate lipid solubility, lack of intrinsic sympathomimetic activity (ISA), and weak membrane stabilizing activity (MSA). |
| Mechanism of action | Metoprolol competes with adrenergic neurotransmitters such as catecholamines for binding at beta(1)-adrenergic receptors in the heart. Beta(1)-receptor blockade results in a decrease in heart rate, cardiac output, and blood pressure. |
| Absorption | Rapid and complete, 50% |
| Volume of distribution | Not Available |
| Protein binding | 12% |
| Metabolism | Primarily hepatic |
| Route of elimination | Less than 5% of an oral dose of metoprolol is recovered unchanged in the urine; the rest is excreted by the kidneys as metabolites that appear to have no beta-blocking activity. |
| Half life | 3-7 hours |
| Clearance | Not Available |
| Toxicity | LD50=5500 mg/kg (orally in rats), toxic effects include bradycardia, hypotension, bronchospasm, and cardiac failure. LD50=2090 mg/kg (orally in mice) |