Class IV antiarrhythmics: Calcium channel blockers and others

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Class IV antiarrhythmics: Calcium channel blockers and others


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Class IV antiarrhythmics: Calcium channel blockers and others

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Atrial fibrillation

calcium channel blockers for p. 363

Atrioventricular block

calcium channel blockers p. 325, 363

Calcium channel blockers p. 325

angina p. 325

antiarrhythmic drugs p. 363

contractility in p. 292

cutaneous flushing p. 249

gingival hyperplasia p. 251

hypertension p. 325

hypertrophic cardiomyopathy p. 317

migraine headaches p. 536

Raynaud phenomenon p. 484

Constipation p. 572

calcium channel blockers p. 325

Dihydropyridine calcium channel blockers p. 255

Dizziness p. 552

calcium channel blockers p. 325


calcium channel blockers as cause p. 325

Gingival hyperplasia

calcium channel blockers p. 325

Heart failure p. 318

calcium channel blockers p. 363

Hyperprolactinemia p. 250, 334, 544

calcium channel blockers and p. 325

Peripheral edema

calcium channel blockers p. 325

Prinzmetal angina

calcium channel blockers for p. 325

Raynaud phenomenon p. 485

calcium channel blockers for p. 325

Smooth muscle (vascular)

calcium channel blocker action p. 325

Supraventricular tachycardia

calcium channel blockers for p. 363


Antiarrhythmic medications help control arrhythmias, or abnormal heartbeats.

There are four main groups of antiarrhythmic medications: class I, sodium-channel blockers; class II, beta-blockers; class III, potassium-channel blockers; class IV, calcium-channel blockers; and miscellaneous antiarrhythmics, or unclassified antiarrhythmics. Now, we’ll focus on class IV and miscellaneous antiarrhythmics in this video.

First, let’s start with two main types of cells within the heart; pacemaker cells and non-pacemaker cells.

Pacemaker cells build the electrical conduction system of the heart, which consists of the sinoatrial node, or SA node; the atrioventricular node, or AV node; the bundle of His; and the Purkinje fibers.

Pacemaker cells have a special property called automaticity, which is the ability to spontaneously depolarize and fire action potentials.

On the other hand, non-pacemaker cells, also known as cardiomyocytes, make up the atria and ventricles; and they give the heart its ability to contract and pump blood throughout the body.

Now, in contrast to non-pacemaker cells, whose action potential has 5 phases, an action potential in pacemaker cells have only 3 phases.

Here’s a graph of the membrane potential vs. time. Phase 4, also known as the pacemaker potential, starts with the opening of the pacemaker channels.

The current through these channels is called pacemaker current or funny current (If), and it mainly consists of sodium ions.

These sodium ions cause the membrane potential to begin to spontaneously depolarize and as the membrane potential depolarizes, voltage-dependent T-type calcium channels open up, thereby further depolarizing the pacemaker cell.


  1. "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
  2. "Rang and Dale's Pharmacology" Elsevier (2019)
  3. "Hurst's the Heart, 14th Edition: Two Volume Set" McGraw-Hill Education / Medical (2017)
  4. "Effects of L-type calcium channel and human ether-a-go-go related gene blockers on the electrical activity of the human heart: a simulation study" Europace (2014)
  5. "Therapeutic drug monitoring: antiarrhythmic drugs" British Journal of Clinical Pharmacology (1998)
  6. "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)

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