Design and rationale for the WARFA trial: a randomized controlled cross-over trial testing the therapeutic equivalence of branded and generic warfarin in atrial fibrillation patients in Brazil

Background Warfarin is a commonly used anticoagulant. Whether a given dose of the different formulations of Brazilian warfarin will result in the same effect on the international normalized ratio (INR) is uncertain. The aim of the WARFA trial is to determine whether the branded and two generic warfarins available in Brazil differ in their effect on the INR.