Class I Antiarrhythmics - Na Channel Blockers

Question 1

Quinidine (Class, MOA, Indications, AEs)

Answer 1

[Class 1A - Na channel blocker] - Rhythm control

MOA:
- Moderate binding to Na channels –> inc. QRS
- Blocks K channels –> inc. APD
- Blocks ACh

Indications: AF, AFL, PSVT, VT

AE’s: Cinchonism, GI (N/V/D), Thrombocytopenia, Hepatitis, Autoimmune rxn

Question 2

Procainamide (Class, MOA, Indications, AEs)

Answer 2

[Class 1A - Na channel blocker] - Rhythm control

MOA:
- Moderate binding to Na channels –> inc. QRS
- Blocks K channels –> inc. APD
- Blocks ACh

Indications: AF, AFL, PSVT, VT

AE’s: Blocks K channels, autoimmune rxn

Question 3

Disopyramide (Class, MOA, Indications, AEs)

Answer 3

[Class 1A - Na channel blocker] - Rhythm control

MOA:
- Moderate binding to Na channels –> inc. QRS
- Blocks K channels –> inc. APD
- Blocks ACh

Indications: AF, AFL, PSVT, VT

AE’s: Highly cholinergic

Question 4

Lidocaine (Class, MOA, Indications, AEs)

Answer 4

[Class 1B - Na channel blocker] - Rhythm control

MOA:
- Weak binding to Na channels –> no change to QRS
- dec. APD

Indications: ventricular arrhythmias

AE’s: CNS effects

Question 5

Mexiletine (Class, MOA, Indications, AEs)

Answer 5

[Class 1B - Na channel blocker] - Rhythm control

MOA:
- Weak binding to Na channels –> no change to QRS
- dec. APD

Indications: ventricular arrhythmias

AE’s: Gastic AE’s (nausea + vomiting)

Question 6

Flecainide (Class, MOA, Indications, CI, AEs)

Answer 6

[Class 1C - Na channel blocker] - Rhythm control

MOA:
- Strong binding to Na channels –> severely inc. QRS
- no change to APD

Indications: AF + AFL, may be used for ventricular arrhythmias

CI: HF, CAD
AE’s: GI + CNS effects

Question 7

Propafenone (Class, MOA, Indications, CI, AEs)

Answer 7

[Class 1C - Na channel blocker] - Rhythm control

MOA:
- Strong binding to Na channels –> severely inc. QRS
- no change to APD

Indications: AF + AFL, may be used for ventricular arrhythmias

CI: HF, CAD, asthma/COPD (for propafenone)

AE’s: beta blocker effects, metallic taste, GI + CNS effects