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
How does Adenosine work and when do we use it?
↓ AV nodal conduction Supraventricular arrhythmias
Side effects of Adenosine
Flushing, hypotension, chest pain
How does Magnesium work and when do we use it?
We don’t know how it works… Use it for Torsades de pointes
Side effects of using Mg2+
Respiratory depression