Brands, Medical Use, Clinical Data
- Antihypertensive Agents
- Antiarrhythmic Agents
- Adrenergic Agents
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
For the treatment of hypertension and angina pectoris.
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.
Rapid and complete, 50%
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
Hypertension and Angina: Extended release metoprolol succinate is contraindicated in sinus
bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure
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