1. Block Na channels 2. Block sympathetic activities 3. Prolong effective refractory period (by blocking K channels) 4. Block Ca channels

Anti-Arrhythmic Drugs Flashcards by Genovia Amelia

Action Potential: Pacemaker AP

Phase 4
* Spontaneous depolarization (Pacemaker potential)
* Slow opening of Na Channel

Phase 0
* Rapid depolarization
* Ca channel opening

Phase 3
* Repolarization phase
* K channel opening

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Action Potential: Cardiac Muscle Cells

Phase 4
* Resting Membrane Stae
* Outward leak K+

Phase 0
* Upstroke phase
* Depolarization Phase
* ↑ Na influx

Phase 1
* Partial repolarization
* Rapid opening & closing of K Channel

Phase 2
* Plateau Phase
* ↑ Ca influx
* ↑ K efflux

Phase 3
* Repolarization Phase
* ↑ K efflux

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Arrythmia

Abnormal Heart Rhythm
<60 bpm
>100 bpm

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Therapeutic Goals

Block Na channels
Block sympathetic activities
Prolong effective refractory period (by blocking K channels)
Block Ca channels

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Vaughan-Williams Classification

Class I: Na-channel Blockers
Class II: B-blockers
Class III: K-channel blockers
Class IV: Ca-channel blockers

Na Bi Ka Ca

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MOA of Class IA Drugs

Moderate Na+ Channel Blockers
Prolong action potential duration, QRS Complex, QT Interval

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Class IA Anti-Arrhythmia

Quinidine
Procainamide
Disopyramide

Quini is PromDI
Double Quarter Pound

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Clinical Use of Class IA Anti-Arrhythmia

For ventricular arrhythmia

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S/Es of Class IA Drugs

Torsades De Pointes

Quinidine - Cinchonism, Thrombocytopenia, Diarrhea
Procainamide - SLE-like symptons
Disopyramide - Anticholinergic Symptoms

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Class IB

Mild Na+ Channel Blockers
Shorten Action Potential, QRS Complex, QT Interval

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Class IB Drugs

Tocainamide
Mexilitine
Lidocaine
Phenytoin

To Make Love Please

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S/E of Phenytoin

Gingival Hyperplasia
Nystagmus

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DOC in the treatment in Ventricular Fibrillation

Lidocaine

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Class IC

Strong Na-channel blockers
No effect in the action potential duration
Prolong QRS Complex, QT Interval

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Class IC Drugs

Moracizine
Flecainide
Propafenone
Encainide

More Fries Papa Enchong

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Class II Antiarryhthmics

Esmolol
Metoprolol
Propranolol (Inderal)
Acebutolol

All B-blockers except Sotalol

MOA of Class II Antiarryhthmics

Reduce Heart rate
Prolong AV Node Conduction & Refractory Period

Treat Supraventricular Tahcycardia (SVT) and Ventricular Tachycardia

Class II Antiarrhythmics

MOA of Class III Antiarrhythmics

Block K+ Channels
Prolong Action Potential, QRS Complex, and QT interval

1st treatment in Ventricular Tachycardia & Atrial Fibrillation

Class III Antiarrhythmics

Amiodarone
Bretylium
Ibutilide
Dofetilide
Sotalol

Class III Antiarrhythmic with broadest spectrum and longest DOA

Amiodarone

32% Iodine

Adverse effects of Class III Antiarrhythmics

Amiodarone:
Hepatotoxicity
Pulmonary fibrosis
Wolff-Chaikoff Effect (hypothyroid → hyperthyroidism)
Cardiotoxic
Bluish gray skin
Cornea micro deposits

Class IV Antiarrhythmics

Verapamil
Diltiazem

Used for paroxysmal supraventricular arrhythmia, but not effective in ventricular arrhythmia

Class IV Drugs

1st line treatment in acute Supraventtricular Tachycardia and PSVT

Adenosine

Antiarrhythmic with very short half life (<10s)

Adenosine | A/Es: Bronchospasm

1st line in the mx of Torsades de Pointes

Magnesium sulfate

Increases vagal tone and slows AV node conduction velocity

Digoxin

Used in Atrial fibrillation | (not preferred)

Digoxin

Preferred drugs for Atrial Flutter & Atrial Fibrillation

Metoprolol Amiodarone Verapamil

Preferred drugs for Acute SVT

Adenosine Veraapamil

Preferred drugs for Chronic SVT

B-blockers (Metoprolol) CCBs

Preferred drugs for Acute VT

Amiodarone Lidocaine (IV)

Preferred drugs for Chronic VT

Amiodarone Beta blockers

Preferred drugs for Ventricular fibrillation | Most dangerous

Amiodarone Epinephrine

Amiodarone is preferred drug for

Atrial Flutter Atrial Fibrillation Acute VT Chronic VT Ventricular fibrillation

Verapamil is preferred drug for

Atrial Flutter Atrial Fibrillation Acute SVT