How Do Class IC Antidysrhythmics Work?

Reviewed on 5/18/2021

WHAT ARE CLASS IC 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 IC antidysrhythmics are strong sodium channel blockers with major action on open state channels and have the longest channel recovery time. These drugs do not have a significant effect on action potential, but they have the strongest effect on the initiation phase 0 of depolarization. They delay conduction, prolong P-R interval, and widen the QRS complex. These drugs have a maximum effect on His-Purkinje as well as accessory pathway conduction.

Class IC antidysrhythmics have high proarrhythmic (may cause a new arrhythmia or aggravate a preexisting arrhythmia during therapy) potential and may cause sudden death during therapy.

Antidysrhythmic drugs do not improve the survival rate among patients with nonlife-threatening arrhythmias and may increase mortality in patients with structural heart disease.

HOW ARE CLASS IC ANTIDYSRHYTHMICS USED?

Class IC antidysrhythmics are used to treat the following:

WHAT ARE SIDE EFFECTS OF CLASS IC ANTIDYSRHYTHMICS?

Serious side effects of class IC antidysrhythmics include:

  • Proarrhythmogenic (these drugs are contraindicated immediately after heart attack)
  • Life-threatening ventricular tachycardia (abnormal heartbeats that occur in the lower chambers)
  • QT prolongation (heart muscle takes longer than usual to recover after each beat
  • Congestive heart failure (heart doesn't pump blood as well as it should)
  • Bronchospasm (airways go into spasm and contract)

Other common 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 IC ANTIDYSRHYTHMICS?

Drug names include:

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

https://www.amboss.com/us/knowledge/Antiarrhythmic_drugs

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