Dose proportionality and pharmacokinetics of dronedarone following intravenous and oral administration to rat.

The aim of this study was to investigate the pharmacokinetic properties of dronedarone by using noncompartmental analysis and modeling approaches after intravenous and oral administration of dronedarone to rats. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups, and dronedarone was administered intravenously (1 mg/kg) and orally (5, 10 and 40 mg/kg) based on a parallel design. Blood samples were collected before and 0.083 (intravenous administration only), 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 12 and 24 h after drug administration. The plasma concentration of dronedarone was determined by using LC-MS/MS. The oral bioavailability of dronedarone was evaluated as approximately 16% in rats, similar to that in humans. The assessment of dose proportionality by using the power model showed that AUCinf increased in a dose-proportional manner, whereas AUC24h and Cmax exhibited a lack of dose proportionality over the dose range between 5 and 40 mg/kg. The two-compartment model, with first-order absorption and elimination rate constants, was sufficient to explain the pharmacokinetics of dronedarone with biexponential decay. These findings will help to understand the pharmacology of dronedarone to develop the new formulation and therapeutics optimization linked to pharmacokinetic/pharmacodynamic study.