Pharmacology and Drug Therapy Flashcards

Which class of antiarrhythmic drug works by blocking fast sodium channels?

Answer: Class I

Class I antiarrhythmic drugs block fast sodium channels, slowing phase 0 depolarization and conduction velocity.

Amiodarone is primarily classified under which Vaughan Williams class?

Answer: Class III

Amiodarone is primarily a Class III antiarrhythmic that blocks potassium channels to prolong the action potential and refractory period.

Which antiarrhythmic drug is contraindicated in structural heart disease due to increased mortality demonstrated in the CAST trial?

Answer: Flecainide

Flecainide (Class IC) is contraindicated in structural heart disease because the CAST trial showed it significantly increased mortality in post-MI patients.

What is the primary mechanism by which adenosine terminates paroxysmal SVT?

Answer: Activates A1 receptors causing transient AV block

Adenosine activates A1 receptors on AV nodal cells, increasing potassium conductance and causing transient AV block that interrupts reentrant SVT.

Ibutilide is primarily indicated for acute pharmacological conversion of which arrhythmia?

Answer: Atrial flutter and atrial fibrillation

Ibutilide is an IV Class III agent specifically approved for rapid pharmacological cardioversion of atrial flutter and atrial fibrillation.

Which beta-blocker has an ultra-short half-life of approximately 9 minutes, making it ideal for acute rate control?

Answer: Esmolol

Esmolol has an ultra-short half-life of approximately 9 minutes due to rapid hydrolysis by red blood cell esterases.