Rational quinidine dosage regimen for atrial fibrillation in Thoroughbred racehorses based on population pharmacokinetics.

Introduction: Quinidine (QND) sulfate is an effective treatment for atrial fibrillation (AF) in horses, and several dosage regimens have been proposed to address its wide variability in response and potential adverse effects. The purpose of this study was to analyze the variability in plasma quinidine concentrations using population pharmacokinetics to determine an effective and safe dosage regimen for Thoroughbred horses.

Methods: Six healthy Thoroughbred horses were treated with 20 mg/kg quinidine sulfate dihydrate (16.