Description
Mechanism of Action
Metoprolol selectively inhibits β1-adrenergic receptors but has little or no effect on β2-receptors except in high doses. It does not exhibit membrane stabilising or intrinsic sympathomimetic activity.
Onset: 1-2 hr (oral); 20 min, when infused over 10 min (IV).
Duration: Oral: Approx 3-6 hr (immediate release); approx 24 hr (extended release). IV: 5-8 hr.
Absorption: Absorbed readily and completely from the GI tract. Bioavailability increased by food. Bioavailability: Approx 50%. Time to peak plasma concentration: Approx 1.5-2 hr (oral).
Distribution: Widely distributed, enters breast milk, crosses the placenta and blood-brain barrier. Volume of distribution: 3.2-5.6 L/kg. Plasma protein binding: Approx 12%.
Metabolism: Extensively hepatic via CYP2D6 isoenzyme and undergoes oxidative deamination, O-dealkylation followed by oxidation and aliphatic hydroxylation.
Excretion: Via urine (as metabolites and unchanged drug). Elimination half-life: 3-4 hr (fast hydroxylators); approx 7 hr (poor hydroxylators).
MIMS Class
Beta-Blockers / Antimigraine Preparations
ATC Classification
C07AB02 – metoprolol; Belongs to the class of selective beta-blocking agents. Used in the treatment of cardiovascular diseases.;
