In this article we briefly discuss the anti-arrhythmic classes and give examples of each type. This would come into play as a KFP or an OSCE question when faced with a case involving palpitations. or after diagnosing a specific arrhythmia. 

What are the four classes of anti-arrhythmic medications?

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Class I Antiarrhythmics – Fast Sodium (Na) Channel blockers, they suppress phase 0

Class II Antiarrhythmics (Beta Blockers) Decrease slope of phase 4

Class III Antiarrhythmics Potassium Channel Blockers (Prolong Phase 3)

Class IV Antiarrhythmics Slow Calcium (Ca) channel blockers (Phase 2)

 

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Class I Antiarrhythmics – What phase of the action potential do they work on?

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Fast Sodium (Na) Channel blockers, they suppress phase 0

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What are the subclasses and example of class 1 Antiarrhythmics ?

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Class Ia Antiarrhythmics

• Procainamide (depress phase 0)

Class Ib Antiarrhythmics

• Phenytoin
• Lidocaine

Class Ic Antiarrhythmics

• Flecainide (markedly depress phase 0)

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How do Class II Antiarrhythmics (Beta Blockers) work?

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Decrease slope of phase 4

 

 

 

 

 

 

 

 

 

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What are some drug names, doses, frequency, duration for Class 2 Antiarrhythmics?

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• Propanolol
• Timolol
• Metoprolol
• Atenolol

(not complete, clearly)

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How do Class III Antiarrhythmics  work?

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Potassium Channel Blockers (Prolong Phase 3)

 

 

 

 

 

 

 

 

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What are some drug names, doses, frequency, duration for Class 3/III Antiarrhythmics?

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• Amiodarone 200mg – 400mg daily
• Sotalol 80-160mg BD

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How do Class IV Antiarrhythmics  work?

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Slow Calcium (Ca) channel blockers (Phase 2)

 

 

 

 

 

 

 

 

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What are some drug names, doses, frequency, duration for Class 4/IV Antiarrhythmics?

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• Verapamil 160-480mg daily (prolongs phase 2)
• Diltiazem 180-360mg daily (prolongs phase 2)

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