Pharmacology and Drug Therapy Flashcards

Procainamide's active metabolite NAPA primarily exhibits which class of antiarrhythmic activity?

Answer: Class III

NAPA (N-acetylprocainamide) is a Class III antiarrhythmic that blocks IKr, prolonging the action potential duration and QT interval.

What INR range is targeted for warfarin anticoagulation in atrial fibrillation for stroke prevention?

Answer: 2.0–3.0

The target INR for stroke prevention with warfarin in non-valvular atrial fibrillation is 2.0–3.0, balancing thromboembolic and bleeding risk.

Which direct oral anticoagulant (DOAC) acts as a direct thrombin inhibitor rather than a factor Xa inhibitor?

Answer: Dabigatran

Dabigatran directly inhibits thrombin (factor IIa), whereas rivaroxaban, apixaban, and edoxaban are all factor Xa inhibitors.

Lidocaine (Class IB) is most effective for treating which type of arrhythmia?

Answer: Ventricular tachycardia and fibrillation

Lidocaine preferentially suppresses ischemic myocardium and is used for ventricular tachycardia and fibrillation, particularly in the setting of acute myocardial infarction.

Verapamil's mechanism for treating AV nodal-dependent tachycardias is primarily?

Answer: L-type calcium channel blockade in the AV node

Verapamil blocks L-type calcium channels in the AV node, slowing conduction and prolonging the AV nodal refractory period to terminate or prevent reentrant tachycardias.

Quinidine syncope is caused by which ECG and electrophysiological phenomenon?

Answer: Torsades de pointes from QT prolongation

Quinidine syncope results from torsades de pointes caused by quinidine's potassium channel blocking effect prolonging the QT interval.