Comparison of the clinical efficacy of three brands of warfarin

OBJECTIVE: To compare the clinical efficacy of three brands of warfarin. MATERIAL AND METHODS: Thirty-six patients (mean age 51.8±12.7 years, 12 males, 24 females) with different indications for anticoagulant therapy were randomly placed in 3 groups. Each group started with one of the three brands of warfarin (Orion from Finland=Brand A, Cipla from India=Brand B and Ferrer from Spain=Brand C) and crossed over to another after 4 weeks. Patients were followed up at weekly visits, checking prothrombin time (PT), International Normalized Ratio (INR) and any complications. The cardiologist and patients were unaware of the warfarin brand used. Number of dose changes, mean dose changes (mg), target INR achievement in the last week and the mean stable dose (mg) were compared between the three brands. RESULTS: Mean number of dose changes throughout the 4-week course was 1.6±1.2 times for brand A, 1.2±1.1 times for brand B and 1.3±0.9 times for brand C (P =0.24). The amount of total dose changes was similar (0.70±0.6 mg for brand A, 0.63±0.9 mg for brand B and 0.72±0.8 mg for brand C, P =0.89). The rate of target INR achievement in the last week was similar (46.9% for brand A, 50% for brand B and 50% for brand C). Thirty-four per cent of patients treated with brand A, 28% with brand B, and 32% with brand C did not achieve target INR. The required dose for the stable target INR was 4.6±2.2 mg, 5.3±2.2 mg and 5.3±2.4 mg in patients treated with brands A, B and C respectively (P =0.61). There were no complications except 2 cases of drug discontinuation by the physician for extreme overdose, (i.e. INR>4.5 that needed drug discontinuation). CONCLUSION: Orion, Cipla and Ferrer warfarin products were similar regarding target INR achievement, the required dose and number of dose changes.