Plasma flecainide concentrations following acute myocardial infarction

Area of Science:

• Cardiology
• Pharmacology
• Internal Medicine

Background:

• Acute myocardial infarction (AMI) presents challenges for antiarrhythmic drug therapy.
• Flecainide is a Class Ic antiarrhythmic agent.
• Understanding drug bioavailability is crucial for effective treatment post-AMI.

Purpose of the Study:

• To evaluate plasma flecainide concentrations in patients with acute myocardial infarction.
• To assess the variability and predictability of oral flecainide dosing.
• To determine the safety and efficacy of flecainide in this patient population.

Main Methods:

• 10 patients with acute myocardial infarction were enrolled.
• Oral loading dose of 300 mg flecainide was administered.
• Subsequent maintenance doses of 150 mg twice daily were given.
• Plasma flecainide concentrations were monitored.

Main Results:

• Oral loading doses resulted in highly variable and unpredictable plasma flecainide concentrations.
• Maintenance doses of 150 mg twice daily achieved mean concentrations above 400 µg/L within 48 hours.
• Six patients experienced mild pulmonary edema, which resolved with frusemide treatment.

Conclusions:

• Oral flecainide exhibits variable bioavailability in AMI patients, similar to other antiarrhythmics.
• Intravenous administration of flecainide is initially preferable due to absorption variability.
• Flecainide should be used cautiously in patients with suspected left ventricular dysfunction due to the risk of pulmonary edema.