BackgroundConcurrent use of dronedarone and oral anti-coagulants are common since both classes of medications are essential to atrial fibrillation management. Dronedarone is a moderate inhibitor of CYP3A4 and P-glycoprotein (P-gp). To date, no drug-drug interaction (DDI) studies between dronedarone and apixaban or rivaroxaban were reported. The current study aims to study the impact of dronedarone co-administration on exposure of apixaban or rivaroxaban with physiologically based pharmacokinetic (PBPK) modeling.MethodModeling and simulation were conducted with Simcyp Simulator. The input parameters required for dronedarone modeling were obtained from literature. The developed dronedarone PBPK model was extensively validated with reported DDIs between dronedarone and CYP3A4 and P-gp substrates. After model validation, the model was applied to evaluate DDI potential of dronedarone on exposure of apixaban or rivaroxaban in both healthy population and patients with renal impairment.ResultThe developed PBPK models accurately describe dronedarone pharmacokinetics following single-dose oral administration in healthy volunteers. The model also predicts DDIs between dronedarone and CYP3A4 and P-gp substrates well, with all fold errors less than 1.5. The AUC of apixaban was increased by 1.36-fold in healthy population due to dronedarone co-administration. In addition, for patients with moderate renal impairment, the AUC of apixaban and rivaroxaban would increase by 1.38-fold and 1.25-fold, respectively.ConclusionsThe established PBPK model of dronedarone was well validated with previously reported DDI studies. Reduced dosing regimens were recommended for patients administered apixaban and dronedarone together. For patients with renal impairment, both dosages of apixaban and rivaroxaban should be adjusted to avoid overexposure when dronedarone is co-administered.