Safe and efficacious dosage of flecainide acetate for treating equine atrial fibrillation.

The research article presents findings on the optimal dosage of flecainide acetate to safely and effectively treat atrial fibrillation, a heart disorder, in horses.

Study Design and Methodology

• The study was conducted to uncover a safe and effective dose of flecainide acetate for the treatment of equine atrial fibrillation. The atrial fibrillation is an abnormal heart rhythm characterized by rapid and irregular beating and is common in horses.
• The researchers conducted tests by injecting 1, 2, or 3 mg/kg of a 1% solution of flecainide acetate intravenously at a rate of 0.2 mg/kg/min to five healthy horses.
• During this trial, the horses’ heart rate, PR interval (the time from the start of the P wave to the start of the QRS complex on an ECG), QRS duration, and QT interval were all closely monitored. Additionally, blood samples were taken to measure the plasma flecainide concentration before and after drug administration.

Resuts and Observations

• No abnormal clinical signs were observed in horses that received either 1 or 2 mg/kg of flecainide acetate. However, agitation was observed in three out of five horses of the 3 mg/kg group.
• Electrocardiogram (ECG) results for the 3 mg/kg group showed significantly increased QRS and QT intervals, which indicates altered electrical conduction within the heart.
• The levels of flecainide in the plasma of the horses increased with the dosage, reaching peak concentrations for the 1, 2, and 3 mg/kg groups, respectively.

Efficacy Evaluation

• Next, atrial fibrillation was artificially induced in six healthy horses. Flecainide was then administered until sinus rhythm was restored.
• All horses with induced atrial fibrillation returned to sinus rhythm. The average dose required was 1.4 mg/kg, administered over about 7 minutes.
• The average plasma concentration of flecainide at conversion to sinus rhythm was 1,303 ng/ml.

Conclusions

• The data suggest that flecainide acetate is safe and effective for treating equine atrial fibrillation. The optimal dosage range was found to be between 1 and 2 mg/kg.
• From the study, it is important to note that administering dosages higher than 2mg/kg may result in side effects such as agitation and alterations in heart conduction.