Glass III antiarrhythmic drugs like amiodarone primarily work by:

A Blocking sodium channels

B Blocking potassium channels to prolong the action potential duration and refractory period

C Blocking calcium channels

D Blocking beta receptors

✓ Correct Answer: Option B

Class III antiarrhythmics: K+ channel blockers → prolonged AP duration and ERP → prolonged QT. Amiodarone has properties of all 4 classes. Used for atrial and ventricular arrhythmias.

💡 Why is B) the correct answer?

The correct answer to the question "Glass III antiarrhythmic drugs like amiodarone primarily work by:" is Option B: Blocking potassium channels to prolong the action potential duration and refractory period.

The other options — A) Blocking sodium channels, C) Blocking calcium channels, D) Blocking beta receptors — are incorrect for this USMLE Exam Prep question. As explained above: Class III antiarrhythmics: K+ channel blockers → prolonged AP duration and ERP → prolonged QT. Amiodarone has properties of all 4 classes. Used for atrial and ventricular arrhythmias.

📚 About This USMLE Exam Prep Practice Question

This 3-level USMLE Exam Prep question from the Step 1 - Basic Sciences topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free USMLE Exam Prep practice test or use flashcards for spaced repetition review.

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Glass III antiarrhythmic drugs like amiodarone primarily work by:

✓ Correct Answer: Option B

📚 About This USMLE Exam Prep Practice Question

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