Metoprolol

Class Beta blocker
Chemistry

aryloxypropanolamine

Routes of administration

Oral or IV

Absorption

50% oral bioavailability

Solubility

pKa 9.7, poor lipid solubility

Distribution

VOD 2.8-4.8 L/kg; only 12% protein bound

Metabolism

Mainly hepatic clearance

Elimination

minimal renal excretion; half-life 3-4 hrs

Time course of action

Clinical effects persist for longer than the half life would suggest, because they are mainly determined by drug-receptor affinity

Target receptor

Selective β1 receptor blocker

Mechanism of action

By binding to Gs-protein coupled β1 receptors, blocks cAMP synthesis

Clinical effects

β1 effects: decreased heart rate, cdecreased contractility, decreased blood pressure, lower myocardial oxygen demand and increased diastolci coronary fillng, and decreased arrhythmogenicity.

Literature reference

Oliver et al (2019)

CICM details of understanding Not specifically listed in the CICM syllabus
Mentioned around Deranged Physiology
Related SAQs