Verapamil !

A calcium channel blocker that acts mostly on the heart: it slows the AV node. Used for angina, high blood pressure and supraventricular arrhythmias.

Updated 2026-11-01

Class: Calcium channel blockers
Ion channel: L-type voltage-gated calcium channel (CaV1.2)
ATC code: C08DA01
WHO Model List of Essential Medicines

L-type voltage-gated calcium channel (CaV1.2)Verapamil

The figure shows verapamil bound inside the pore of the rabbit skeletal-muscle L-type channel CaV1.1, which shares the binding site with the cardiac channel CaV1.2.

Target in 3D: L-type voltage-gated calcium channel (CaV1.2). PDB structure 6JPA (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Verapamil, a phenylalkylamine, enters the L-type calcium channel pore from the inside and blocks it more when the channel opens often (use dependence). It slows the sinus node and, above all, AV conduction, lowers contractility and dilates arterioles and coronary arteries. That makes it useful to slow the ventricles in atrial fibrillation and to stop re-entry through the AV node.

Verapamil blocks the L-type calcium channel from inside the pore
The AV node conducts more slowly and the sinus node slows
Contractility falls and arterioles dilate

Pharmacokinetics

Absorption: Well absorbed but with a large first-pass loss, so oral bioavailability is low
Metabolism: Liver, by CYP3A4 and other enzymes; inhibitors and inducers change its levels
Half-life: Longer with repeated dosing, in liver disease and in older adults

Indications

Rate control in atrial fibrillation or flutter Atrial fibrillation →
Paroxysmal supraventricular tachycardia (prevention, and conversion with the IV form)
Angina, including vasospastic angina Stable angina →
High blood pressure Arterial hypertension →

Adverse effects

Common

Constipation, the most common
Dizziness and headache
Bradycardia
Oedema
Hypotension

Contraindications

Severe left ventricular dysfunction
Hypotension or cardiogenic shock
Sick sinus syndrome or second- or third-degree AV block without a pacemaker
Atrial fibrillation or flutter with an accessory pathway (WPW)
IV form: IV beta blockers given within a few hours

Key interactions

Beta blockers: Added bradycardia, AV block and heart failure
Digoxin: Digoxin levels rise; digoxin is adjusted
Statins metabolised by CYP3A4 (simvastatin, lovastatin): Higher statin levels and myopathy
Grapefruit juice and alcohol: Grapefruit raises verapamil levels; verapamil raises and prolongs blood alcohol

What is monitored

Heart rate, blood pressure and ECG (PR interval)
Continuous ECG during IV use
Digoxin level when combined
Bowel habit

Administration and safety

Extended-release tablets are not crushed or chewed
IV form: given slowly with continuous ECG and blood pressure monitoring, and never close in time to an IV beta blocker
Before IV use, check that the rhythm is not a wide-complex tachycardia or atrial fibrillation with WPW

Nursing care

Check apical pulse and blood pressure before doses; report bradycardia or hypotension
Prevent and ask about constipation (fluids, fibre)
Watch for signs of heart failure: breathlessness, oedema, weight gain
Teach the patient to avoid grapefruit and limit alcohol

Pregnancy and breastfeeding

Human data are limited; it crosses the placenta and is used in pregnancy only when clearly needed.

Test yourself

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

What is the most common adverse effect of verapamil?

Constipation.

Why is verapamil dangerous in atrial fibrillation with WPW?

Blocking the AV node favours conduction down the accessory pathway, with a very fast ventricular rate or ventricular fibrillation.

What happens to digoxin levels when verapamil is added?

They rise, so the digoxin is adjusted and its level is checked; AV block also adds up.

Why is IV verapamil not given right after an IV beta blocker?

Both depress contractility and AV conduction; together they can cause severe bradycardia, block or asystole.

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

Sources: DailyMed - VERAPAMIL HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - VERAPAMIL HYDROCHLORIDE injection, solution (DailyMed (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).

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Representative model, for educational purposes only.