Lecture 15: Anti-arrythmic drugs

Question 1

Quinidine, Procainamide, Disopyramide

Answer 1

Class 1

Type A Na channel blockers

for ventricular arrhythmia

Question 2

Lidocaine, Mexiletene

Answer 2

Class 1

Type B Na channel blockers

rapid kinetics faster onset and offset

Question 3

Propafenone, Flecainide

Answer 3

Class 1

Type C Na channel blockers

slower onset and offset

drug effect accumulates

Question 4

Amiodarone, Sotalol, Dronedarone, Dofetilide

Answer 4

Class 3

K Channel blockers

Question 5

Class 1A, B, C antiarrhythmic effects on ventricular action potential

Answer 5

Class 1A: prolong action potential, slow rate of upstroke (increase QRS and QT)

Class 1B: shorten action potential (decrease QT)

Class 1C: slow rate of rise, MOST POTENT in blocking Na channel (increase QRS strongly)

Question 6

Why are arrhythmia hard to treat?

Answer 6

because the disease is EPISODIC

efficacy of anti-arrhythmic drugs can only be assessed by doing placebo controlled clinical trials

Question 7

What are antiarrhythmics used for?

Answer 7

Atrial fibrillation

tachycardia

adjuncts to prevent ventricular tachycardia

Question 8

Prevention of shock from implantable cardioverter defibrillators

Answer 8

Amiodarone + Beta blocker > Sotalol > Beta blocker

Question 9

Flecainide vs Quinidine for treatment of Paroxysmal Atrial Fibrillation

Answer 9

Flecainide

less side effects

less chance for discontinuation

Question 10

Side effect for antiarrhythmics

Answer 10

Proarrhythmias

new or more frequent occurrence of pre-existing arrhythmias

can be predictable

Question 11

Isoproterenol and Class 3 antiarrhythmics

Answer 11

isoproterenol is a non-selective B agonist

sympathetic tone can decrease class 3 antiarrhythmic effects

Question 12

Risks of class 1, 2, 3, 4 antiarrhythmic drugs

Answer 12

Class 1: sudden death (unknown mechanism)

Class 2: Fatigue, bradycardia

Class 3: Torsades de pointes VT

Class 4 (ca channel blockers, non-DHP): worsening of heart failure, bradycardia