Test Catalog

Test ID: PFN    
Propafenone, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring propafenone therapy


Assessing potential toxicity 

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Propafenone (Rythmol) is a class 1C cardiac antiarrhythmic used to treat ventricular arrhythmias (ventricular tachycardia, supraventricular tachycardia, and ventricular premature contractions).


Propafenone undergoes extensive first metabolism (half-life is approximately 1-3 hours). Its clinical efficacy is maintained through the formation of a metabolite (5-hydroxypropafenone) that is more pharmacologically active than the parent drug and has a longer half-life (6-12 hours).


Specimens should only be collected after patient has been receiving propafenone orally for at least 3 days. Trough concentrations should be collected just before administration of the next dose. The therapeutic concentration is 0.5-2.0 mcg/mL; concentrations less than 0.5 mcg/mL likely indicate inadequate therapy, and propafenone above  2.0 mcg/mL indicates excessive therapy. Adverse side effects are seen in the central nervous system, skin, and gastrointestinal tract.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Trough Value

0.5-2.0 mcg/mL: Therapeutic concentration

>2.0 mcg/mL: Toxic concentration

Interpretation Provides information to assist in interpretation of the test results

The therapeutic concentration is 0.5 to 2.0 mcg/mL; concentrations below 0.5 mcg/mL likely indicate inadequate therapy and propafenone above 2.0 mcg/mL indicates excessive therapy.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Specimens that are obtained from gel tubes or anticoagulate collections can cause assay interference.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Nader R, Horwath AR, Wittwer CT: In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Sixth edition. St. Louis: Elsevier 2018

2. Burtis CA, Ashwood ER, Bruns DE, et al: In Tietz Textbook of Clinical Chemistry and Molecular Diagnosis. Fifth edition. St Louis: Elsevier. USA 2012

3. Josephson ME, Buxton AE, Marchlinski FE: The tachyarrhythmias: tachycardias. In Harrison's Principles of Internal Medicine. 12th edition. Edited by JD Wilson, E Braunwald, KJ Isselbacher, et al: New York, McGraw-Hill Book Company, 1991, p 915

4. Valdes R Jr, Jortani SA, Gheorghiade M, et al: Standards of Laboratory Practice: Cardiac Drug Monitoring. Clin Chem 1998;44(5):1096-1099

5. Joseph SP, Holt DW: Electrophysiological properties of mexiletine assessed with respect to plasma concentrations. Eur J Cardiol 1980 Feb;11(2):115-121