3.2.2. Antiarrythmic Drugs I and II Flashcards
What are Class I drugs?
Na+ channel blockers
What are class II drugs?
Beta Blockers
What are class III drugs?
K+ channel blockers
What are class IV drugs?
Ca2+ channel blockers
What do the subtypes of Class I do?
IA - ↓ ventricular conduction (↑ QRS interval); prolong ventricular AP (↑ QT interval)
IB - slow conduction and ↑ threshold for firing of abnormal cells
IC - ↓ ventricular conduction (↑ QRS interval)
When do we use each of the subtypes of class I drugs?
IA - Atrial and ventricular arrhythmias IB - Acute ventricular arrhythmias IC - Ventricular arrhythmias
Examples of Class IA drugs
Quinidine, procainamide, disopyramide
Example of Class IB drugs
Lidocaine
Examples of Class IC drugs
Flecainide, propafenone
Side effects of Class IA drugs
Quinidine: cinchonism (headache, tinnitus) and torsades de pointes (polymorphic ventricular tachycardia due to ↑ QT interval);
procainamide: drug-induced lupus like symptoms
Side effects of Class IB drugs
CV and CNS depression w/ overdose
Side effects of Class IC drugs
Can cause arrhythmias (especially in post-MI patients)
How do Beta blockers work?
↓ AV nodal conduction (↑ PR interval)
When do we use beta blockers?
Ventricular and supraventricular arrhythmias
Side effects of Beta Blockers?
Bradycardia, AV block
Propanolol - Can cause bronchoconstriction
Examples of Beta Blockers
Esmolol (IV, rapid acting), metroprolol, propranolol
How do class III drugs work?
Prolong ventricular AP (↑ QT interval)
When do we use Class III drugs?
Treatment and prevention of ventricular arrhythmias
Examples of Class III drugs?
Amiodarone, sotalol, Ibutilide, Dofetilide (AIDS)
Side effects of class III drugs?
Amiodarone: pulmonary fibrosis, hepatotoxicity, thyroid disease
How do class IV drugs work?
↓ AV nodal conduction
When do we use class IV drugs?
Supraventricular arrhythmias
Examples of Class IV drugs?
Verapamil, diltiazem
Side effects of class IV drugs
Constipation, bradycardia, AV block