Active ingredient: Metoprolol - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

• Sympatholytics
• Antihypertensive Agents
• Antiarrhythmic Agents
• Adrenergic Agents

Dosage Forms

• Tablet

Brands / Synonyms

Beloc; Betaloc; Dutoprol; Lopresor; Lopresoretic; Lopressor; Lopressor HCT; Metoprolol; Metoprolol and Hydrochlorothiazide; Metoprolol Tartrate; Metroprolol; Prelis; Selo-Zok; Seloken; Selopral; Toprol; Toprol-XL; Toprol-XL

Indications

For the treatment of hypertension and angina pectoris.

Pharmacology

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

Like betaxolol and atenolol, metoprolol competes with adrenergic neurotransmitters such as catecholamines for binding at beta(1)-adrenergic receptors in the heart and vascular smooth muscle. Beta(1)-receptor blockade results in a decrease in heart rate, cardiac output, and blood pressure.

Absorption

Rapid and complete, 50%

Toxicity

LD₅₀=5500 mg/kg (orally in rats), toxic effects include bradycardia, hypotension, bronchospasm, and cardiac failure. LD₅₀=2090 mg/kg (orally in mice)

Biotrnasformation / Drug Metabolism

Primarily hepatic

Contraindications

Hypertension and Angina: Extended release metoprolol succinate is contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure

Drug Interactions

Catecholamine-depleting drugs (e.g., reserpine) may have an additive effect when given with beta-blocking agents. Patients treated with extended release metoprolol succinate plus a catecholamine depletor should therefore be closely observed for evidence of hypotension or marked bradycardia, which may produce vertigo, syncope, or postural hypotension.