UMEM Educational Pearls

Category: Toxicology

Title: The "Other" Sodium Channel Blocking Agents

Keywords: sodium channel block, tricyclic antidepressant, cocaine, QRS (PubMed Search)

Posted: 5/13/2010 by Bryan Hayes, PharmD (Updated: 12/9/2022)
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We are all familiar with the classic ECG abnormalities caused by the sodium channel blocking properties of tricyclic antidepressants (QRS interval widening, R wave in aVR, S wave in I and aVL, and rightward deviation in terminal 40 msec of QRS). Here are some other medications that also block cardiac sodium channels in a similar manner:

  • Cocaine
  • Diphenhydramine
  • Cyclobenzaprine (Flexeril)
  • Carbamazepine (Tegretol)
  • Phenothiazines
  • Propoxyphene
  • Class 1A antidysrhythmics (quinidine, procainamide, disopyramide)
  • Class 1C antidysrhythmics (encainide, flecainide, propafenone, moricizine)
  • Amantadine