How Do Class IV Antidysrhythmics Work?

Reviewed on 5/24/2021

WHAT ARE CLASS IV ANTIDYSRHYTHMICS AND HOW DO THEY WORK?

Antidysrhythmics, also known as antiarrhythmics, are drugs used to prevent abnormal cardiac rhythms such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. These drugs work by blocking sodium, potassium, and calcium channels in the heart muscles. Some drugs show autonomic effects.

Antiarrhythmic drugs are grouped into four main classes:

  • 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.

Class IV antidysrhythmic drugs inhibit the slow calcium channel inward current. They decrease the slop of phases 0 and 4 and prolong phase 2 of the cardiac action potential. They reduce the conduction velocity and increase the effective refractory period (resting state in a depolarized cardiac cell) and prolong atrioventricular node repolarization and P-R interval.  

HOW ARE CLASS IV ANTIDYSRHYTHMICS USED?

Class IV antidysrhythmic drugs are used to treat:

WHAT ARE SIDE EFFECTS OF CLASS IV ANTIDYSRHYTHMICS?

Serious side effects of class IV antidysrhythmics include:

  • Reflex tachycardia (increased heart rate in response to the stimulus of decreased blood pressure which is transmitted via the cardiac nerves)
  • Heart block (an abnormal heart rhythm where the heart beats too slowly)
  • Bradycardia (slow heart rate)

Other side effects include:

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

QUESTION

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WHAT ARE DRUG NAMES OF CLASS IV ANTIDYSRHYTHMICS?

Drug names include:

References
https://reference.medscape.com/drugs/antidysrhythmics-iv

https://www.ahajournals.org/doi/pdf/10.1161/CIRCULATIONAHA.118.035455

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