NAPLEX Question of the Week: Ranking Antiarrhythmics

Hi everyone! This week we will test your ability to rank antiarrythmics by their mechanism of action and thus class!
NAPLEX Question of the Week: Ranking Antiarrhythmics
Like

Share this post

Choose a social network to share with, or copy the URL to share elsewhere

This is a representation of how your post may appear on social media. The actual post will vary between social networks

Rank the following in order from class I antiarrhythmic to class IV antiarrhythmic.

A. Dofetilide

B. Diltiazem

C. Metoprolol

D. Procainamide




Answer with rationale:

The correct order is D-C-A-B.

The term "Antiarrhythmics" strikes fear into many pharmacy students. But an organized approach to learning them. In general there are 4 broad classes of antiarrhytmics based on mechanism of action: Classes I, II, III, and IV. Class I agents block sodium channels and are further divided up into Class Ia (intermediate association/dissociation), Ib (fast association/dissociation), and Ic (slow dissociation/association). Examples within these classes include procainamide (1a), lidocaine (1b), and flecainide (1c). Class II agents, such as metoprolol,  possess beta-blocking activity. Class III agents, such as dofetilide, block potassium channels. Dofetilide due to its significant QT prolonging potential is always initiated in the inpatient setting where EKG monitoring can take place. One of the more commonly used antiarrhythmics, amiodarone, is also a Class III antiarrhythmic. Finally Class IV agents, such as diltiazem, block calcium channels.

For more reading on this topic, see our chapter in the 3rd Edition Naplex Review Guide on AccessPharmacy:

https://accesspharmacy.mhmedical.com/content.aspx?bookid=2512§ionid=201032487

Additionally, Dr. Scott Sutton has recorded selected videos on difficult topics for students, one of which is on Antiarrhythmics:

https://accesspharmacy.mhmedical.com/MultimediaPlayer.aspx?MultimediaID=16380801

Create a Free MyAccess Profile

AccessMedicine Network is the place to keep up on new releases for the Access products, get short form didactic content, read up on practice impacting highlights, and watch video featuring authors of your favorite books in medicine. Create a MyAccess profile and follow our contributors to stay informed via email updates.