Propafenone shows class Ic and class II antiarrhythmic effects

Area of Science:

• Pharmacology
• Cardiology
• Clinical Trials

Background:

• Propafenone is a Class Ic antiarrhythmic drug.
• Its beta-blocking effects in humans have been debated.
• Conflicting results exist regarding its beta-blocking properties.

Purpose of the Study:

• To investigate the beta-blocking effects of propafenone in healthy males.
• To determine if a standard dose of propafenone causes clinically significant beta-blockade.
• To assess propafenone's effects on heart rate, blood pressure, and plasma concentrations during exercise.

Main Methods:

• Randomized, double-blind, placebo-controlled, cross-over study.
• Twelve healthy males received 600 mg propafenone or placebo orally.
• Measurements included heart rate, blood pressure, and plasma propafenone levels at rest, during exercise, and recovery.

Main Results:

• Propafenone significantly decreased heart rate (-6%) and systolic blood pressure (-6%) during exercise.
• The rate-pressure product was reduced by 11% during exercise.
• Plasma propafenone concentrations increased during exercise and decreased during recovery.

Conclusions:

• Propafenone exhibits both Class Ic and Class II antiarrhythmic properties.
• A 600 mg oral dose causes clinically significant beta-blockade.
• This dose is suitable for cardioversion of paroxysmal atrial fibrillation, even in patients with structural heart disease.