Serum digoxin concentrations during ethmozine antiarrhythmic therapy.

Area of Science:

• Pharmacology
• Cardiology
• Clinical Trials

Background:

• Investigational antiarrhythmic ethmozine (moricizine HCl) is a Class I agent.
• Digoxin is commonly prescribed for heart failure and atrial fibrillation.
• Potential drug interactions between ethmozine and digoxin require evaluation.

Purpose of the Study:

• To assess the pharmacokinetic interaction between ethmozine and digoxin.
• To determine if ethmozine affects serum digoxin concentrations in cardiac patients.
• To evaluate the antiarrhythmic efficacy of ethmozine.

Main Methods:

• 13 cardiac patients with normal renal function and ventricular arrhythmias received ethmozine.
• Patients were on maintenance digoxin therapy.
• Serum digoxin and ethmozine levels were monitored using radioimmunoassay and HPLC.
• A 4-week placebo-controlled ethmozine protocol was followed by long-term open-label therapy.

Main Results:

• Ethmozine demonstrated significant antiarrhythmic efficacy, suppressing ventricular ectopy by over 90% in 77% of patients.
• Serum digoxin concentrations showed a nonsignificant 10-15% increase during short-term ethmozine dosing.
• Digoxin levels remained statistically similar to placebo throughout short-term and long-term ethmozine therapy.

Conclusions:

• Ethmozine, at an effective antiarrhythmic dose, does not cause clinically significant changes in serum digoxin levels.
• No important pharmacokinetic interaction was observed between ethmozine and digoxin in patients with normal renal function.
• Ethmozine can be considered for treating ventricular arrhythmias in patients on digoxin without significant drug interaction concerns.