Clinical pharmacology of dronedarone: implications for the therapy of atrial fibrillation.

Dronedarone, a recently approved antiarrhythmic agent, is a chemical analog of amiodarone. It has an approximately 15% bioavailability, with plasma concentrations markedly increasing after a high-fat meal; it is recommended to be taken with food. The primary metabolic clearance pathway for dronedarone is via the hepatic enzyme system (primarily cytochrome P450 3A4 [CYP3A4]); the half-life of dronedarone is 27 to 31 hours. Strong CYP3A4 inhibitors, such as ketoconazole, are associated with a marked increase in dronedarone maximum concentration and are thus contraindicated; inducers of CYP3A4 will conversely decrease dronedarone exposure. Dronedarone is a substrate for P-glycoprotein (P-gp) and will lead to an increase in concentration of P-gp substrates such as digoxin. Dronedarone will cause a small increase in creatinine concentrations, without a change in glomerular filtration rate (GFR). Gender, renal dysfunction, weight, and age have little effect on the pharmacokinetics of dronedarone, and dose adjustment for these variables is not required.