DurgicalDurgical
EN
Open the app

Pharmacology · Beta blockers

Metoprolol !

A beta blocker that mainly acts on the heart (β1). It slows the heart rate and is used in angina, after a heart attack and in heart failure.

Updated 2026-11-01

  • Class: Beta blockers
  • Receptor: β1-adrenergic receptor
  • ATC code: C07AB02

The figure shows the turkey β1 receptor with cyanopindolol, another beta blocker that sits in the same binding site where metoprolol acts.

Target in 3D: β1-adrenergic receptor. PDB structure 2VT4 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Metoprolol blocks mainly β1 receptors in the heart, slowing the sinus node and AV conduction and reducing contractility, so the heart uses less oxygen. In the kidney it lowers renin release. Its β1 selectivity is relative: it fades as concentrations rise, so bronchospasm remains possible.

  1. Metoprolol occupies β1 receptors in the heart
  2. Sinus rate and AV conduction slow
  3. Contractility and oxygen demand fall
  4. Less angina and better rate control

Pharmacokinetics

Absorption
Well absorbed by mouth, with notable first-pass metabolism
Distribution
Crosses the blood-brain barrier
Metabolism
In the liver, mainly by CYP2D6 (levels vary with genetic type)
Elimination
Mainly by liver metabolism; very little leaves unchanged in the urine
Half-life
About 3 to 7 hours; the extended-release succinate form gives an even effect over the day

Indications

Adverse effects

Common

  • Tiredness
  • Bradycardia and dizziness
  • Cold extremities
  • Diarrhoea

Contraindications

  • Marked bradycardia or second- or third-degree AV block without a pacemaker
  • Cardiogenic shock or acute decompensated heart failure
  • Sick sinus syndrome without a pacemaker

Key interactions

Verapamil or diltiazem
Severe bradycardia, AV block and hypotension
CYP2D6 inhibitors (paroxetine, fluoxetine)
Higher metoprolol levels and more bradycardia
Insulin or sulfonylureas
Hypoglycaemia warning signs may be masked
Digoxin or clonidine
Additive bradycardia; beta blockers can worsen the rebound hypertension when clonidine is stopped

What is monitored

  • Heart rate and blood pressure
  • Signs of heart failure when starting or increasing treatment
  • Blood glucose in people with diabetes

Test yourself

Think of the answer, then tap the question to see it.

What does it mean that metoprolol is cardioselective, and what is the limit of that?

It blocks β1 (heart) receptors more than β2 (bronchi and vessels). Selectivity is relative and decreases as concentrations rise, so bronchospasm can still occur.

Which metoprolol formulation has shown lower mortality in heart failure with reduced ejection fraction?

Metoprolol succinate, the extended-release form, added to stable patients and raised gradually.

Why can paroxetine raise metoprolol's effect?

Metoprolol is cleared mainly by CYP2D6; paroxetine inhibits that enzyme, so levels rise and bradycardia is more likely.

In atrial fibrillation, how does metoprolol slow the ventricular rate?

By blocking β1 at the AV node: conduction slows and the refractory period lengthens, so fewer atrial impulses reach the ventricles.

Add to my cards (4)

← Back to the class: Beta blockers

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Metoprolol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); DailyMed - METOPROLOL SUCCINATE- metoprolol succinate er tablets tablet, film coated, extended release (DailyMed (U.S. National Library of Medicine), 2026).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.