Cardiovascular Pharmacology: Antiarrhythmic Drugs

Flashcards for Cardiovascular Pharmacology - Antiarrhythmic Drugs

What diseases should you be able to list the drugs used in the treatment of?

Supraventricular tachycardia, ventricular tachycardia, and heart block.

What is the mechanism of action of Class I antiarrhythmic drugs?

Na+ channel blockers (Broad spectrum except Class IB)

List examples of Class Ia antiarrhythmic drugs.

Procainamide, Quinidine, Disopyramide

List examples of Class Ib antiarrhythmic drugs.

Lidocaine, Phenytoin, Mexilitine, Tocainide

List examples of Class Ic antiarrhythmic drugs.

Propafenone, Flecainide, Encainide

What is the spectrum of Class II beta blockers?

Broad spectrum

List examples of Class III K+ channel blocker antiarrhythmic drugs.

Amiodarone, Sotalol, Ibutilide, Dofetilide

List examples of Class IV Ca+2 channel blocker antiarrhythmic drugs.

Verapamil and Diltiazem

List non-classified antiarrhythmic drugs.

Adenosine and Digoxin

What is the rate of dissociation and action of Class Ia antiarrhythmics?

Moderate rate of dissociation → Moderate ↓ conductivity and automaticity.

What is the rate of dissociation and action of Class Ib antiarrhythmics?

Rapid rate of dissociation → minimal effect on normal conduction.

What is the rate of dissociation and action of Class Ic antiarrhythmics?

Slow rate of dissociation → Marked ↓ conductivity and automaticity.

What is the effect of Class Ia drugs on Action Potential Duration (APD) and Effective Refractory Period (ERP)?

↑ APD / ↑↑ ERP

What is the effect of Class Ib drugs on Action Potential Duration (APD) and Effective Refractory Period (ERP)?

↓↓ APD / ↓ ERP

What is the effect of Class Ic drugs on Action Potential Duration (APD) and Effective Refractory Period (ERP)?

= APD / ↑ ERP

What is a potential side effect of Class Ia drugs when combined with digitalis, beta blockers, or verapamil?

Paradoxical ventricular Tachycardia in Atrial flutter or AF

What is the impact of Class Ib drugs on conduction and automaticity in depolarized tissue (e.g., ischemic)?

Marked conduction block, ↓ automaticity

What are the uses of Class Ia antiarrhythmics?

Broad spectrum + WPW Syndrome

What are the uses of Class Ib antiarrhythmics?

Ventricular arrhythmia in cardiac surgery, MI, digitalis toxicity

What are the uses of Class Ic antiarrhythmics?

SV arrhythmia (AF, Atrial flutter, PSVT), Ventricular arrhythmia in resistant cases

What are the side effects of Class Ia antiarrhythmics?

Hypotension, Torsade de points arrhythmia, Thromboembolism, SLE

Regarding CVS side effects, how toxic is Class Ib antiarrhythmics?

Least cardiotoxic

What are the CNS side effects of Class Ib antiarrhythmics?

Perioral paresthesia, dizziness, tremors, convulsions

What are the CVS side effects of Class Ic antiarrhythmics?

Arrhythmia, AV block, Heart failure

What are the side effects of Class Ic antiarrhythmics?

Taste disturbances, constipation, Bronchospasm

What is the mechanism of action of Class II antiarrhythmic drugs?

Block β receptors in slow fibers → ↓ SAN and AVN → ↓ slope Phase 4 in pacemakers (slow automaticity)

What is the mechanism of action of Class IV antiarrhythmic drugs?

Block Ca+2 ch in slow fibers → ↓ SAN and AVN → ↓ Slope of phase 4 in pacemakers (slow automaticity)

What are the uses of Class II (Beta Blockers) antiarrhythmic drugs?

Arrhythmia due to sympathetic overactivity: anesthesia, thyrotoxicosis, stress, pheochromocytoma

What are the uses of Class IV antiarrhythmic drugs?

Supraventricular (AF, Atrial flutter)

What is the most important factor about Class III antiarrythmic drugs?

Long t1/2 (35 - 103 days)

What is the mechanism of action of Amiodarone?

Blocks K+, Na+, Ca+2 channels, β blocker

What is the main type of channel that is blocked by Class III antiarrythmic drugs?

K+ channel block (main): delay repolarization, ↑ APD and ↑ ERP in all cardiac tissue and accessory tract → block reentry arrhythmias (PSVT, AF, Atrial flutter)

What is the effect of sodium channel blockade by amiodarone?

Suppress ectopic pacemakers and slow conduction in fast fibers

What is the effect of calcium channel blockade by amiodarone?

Coronary, arterial vasodilation, ↓ sinus rate and ↓ AVN conduction

What are the uses of amiodarone?

Broad spectrum + WPW syndrome

What are the cardiovascular side effects of amiodarone?

bradycardia, HB, hypotension

What are the eye side effects of amiodarone?

Corneal micro deposits (asymptomatic)

What are the thyroid issues side effects of amiodarone?

Hypo or hyperthyroidism

What are the respiratory side effects of amiodarone?

Pulmonary infiltrates and fibrosis

What are the uses of sotalol?

Limited to serious arrhythmias - ventricular arrhythmia, maintenance of sinus rhythm in AF, Atrial flutter

What are the side effects of sotalol?

Torsade de points arrhythmia

What is the mechanism of action of Adenosine?

Binds A1 receptors → Opens K+ ch → hyperpolarization → ↓ Ca+2 influx → ↓ SAN and AVN and ↑ ERP → terminate PSVT

What are the uses of adenosine?

Terminates PSVT

What are the side effects of adenosine?

Chest pain, dyspnea, Headache and flush