A randomized, crossover comparison of warfarin products in the treatment of chronic atrial fibrillation

OBJECTIVE: To compare the dosing requirements and international normalized ratios (INRs) associated with two bioequivalent crystalline warfarin sodium products in patients with chronic atrial fibrillation. METHODS: A multicenter, single-blind (prescriber), randomized, crossover ev aluation of Apothecon warfarin and DuPont warfarin (Coumadin) was conducted in consenting adults with chronic or paroxysmal atrial fibrillation who ha d been receiving DuPont warfarin chronically for the prevention of thromboe mbolism. Patients were randomly assigned to initially either continue DuPon t warfarin or receive Apothecon warfarin for four weeks, with weekly evalua tion of dosage and INR changes, safety, and efficacy. Subsequently. patient s crossed over and received the other product for four weeks. RESULTS: There were 113 patients randomized to receive study treatment. Nei ther the propensity for a dosage change or an INR change nor the magnitude of a dosage change or INR change appeared related to a particular warfarin product (NS for each variable after each study period). After four weeks of treatment, the same number of patients (n = 7) experienced a greater than or equal to 20% change in warfarin dosage from the respective baseline with each product. The number of patients with INRs outside the desired protoco l range after four weeks of treatment was similar for both groups (<1.8, n = 9 for both products, or >3.2, n = 9 for DuPont, n = 10 for Apothecon). No major hemorrhagic or thromboembolic events occurred, CONCLUSIONS: The results of this study show that Apothecon warfarin and DuP ont warfarin provide equivalent anticoagulation in patients with chronic or paroxysmal atrial fibrillation.