Antiarrhythmics Flashcards
What are the Class 1A drugs and what is their MOA?
Quinidine, Procainamide, Disopyramide
They block open and inactivated sodium channels, slowing conduction and increasing refractoriness.
What are indications for use of Class 1A antiarrhythmic drugs?
Atrial, AV junction and ventricular arrhythmias
What are the Class 1B drugs and what is their MOA?
Lidocaine and Mexiletine
Block sodium channels during rapid depolarization phases, shortening the action potential.
What is the indications for use of Class 1B drugs?
Ventricular arrhythmias
What are the Class 1C drugs and what is their MOA?
Flecainide and Propafenone
Strongly inhibits sodium channels and slows conduction.
What are the indications for use of Class 1C drugs?
A fib, atrial flutter, SVT in patients without structural heart disease.
What are the beta blockers and what is their MOA?
“OLOL”
Blocks beta receptors, reducing sympathetic activity, and thereby lowering HR, contractility, and conduction.
What are indications for use of beta blockers?
Tachyarrhythmias, afib, atrial flutter, post MI to reduce arrhythmic mortality.
What are the Class 3 drugs?
Amiodarone, Dronedarone, Sotalol, Dofetilide, Ibutilide
How can you remember the differences between the different potassium channel-blockers?
Amiodarone: “The all-in-one but toxic one.”
Broad mechanism, longest half-life, multiple organ toxicity (thyroid, lungs, liver).
Dronedarone: “Amiodarone lite.”
Less toxic, shorter half-life, but not as effective and contraindicated in heart failure.
Sotalol: “Beta-blocker plus.”
Has both beta-blocking and potassium-blocking effects, watch for bradycardia and QT prolongation.
Dofetilide: “The specialist.”
Pure potassium blocker, highly effective but requires certification to prescribe.
Ibutilide: “IV for emergencies.”
Short-term use for acute rhythm conversion; highest torsades risk.
What are the calcium channel blockers and what is their MOA?
Verapamil, Diltiazem
Blocks calcium channels and slows conduction at the AV node.
What are indications for use of calcium channel blockers for treatment of arrhythmias?
Atrial fibrillation, atrial flutter (atrial arrhythmias)
What is the MOA of digoxin?
Inhibits sodium and potassium, leading to increased calcium, which enhances contractility and vagal tone and slows AV node conduction.
What are indications of use when taking digoxin?
Rate control in afib and aflutter.
What is the MOA of adenosine?
activates adenosine receptors in the AV node which block AV node conduction.
