Anti-Arrhythmic Drugs Flashcards
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
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
Arrythmia
Abnormal Heart Rhythm
<60 bpm
>100 bpm
Therapeutic Goals
- Block Na channels
- Block sympathetic activities
- Prolong effective refractory period (by blocking K channels)
- Block Ca channels
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
MOA of Class IA Drugs
Moderate Na+ Channel Blockers
Prolong action potential duration, QRS Complex, QT Interval
Class IA Anti-Arrhythmia
Quinidine
Procainamide
Disopyramide
Quini is PromDI
Double Quarter Pound
Clinical Use of Class IA Anti-Arrhythmia
For ventricular arrhythmia
S/Es of Class IA Drugs
Torsades De Pointes
Quinidine - Cinchonism, Thrombocytopenia, Diarrhea
Procainamide - SLE-like symptons
Disopyramide - Anticholinergic Symptoms
Class IB
Mild Na+ Channel Blockers
Shorten Action Potential, QRS Complex, QT Interval
Class IB Drugs
Tocainamide
Mexilitine
Lidocaine
Phenytoin
To Make Love Please
S/E of Phenytoin
Gingival Hyperplasia
Nystagmus
DOC in the treatment in Ventricular Fibrillation
Lidocaine
Class IC
Strong Na-channel blockers
No effect in the action potential duration
Prolong QRS Complex, QT Interval
Class IC Drugs
Moracizine
Flecainide
Propafenone
Encainide
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