Evaluation of an Initiation Regimen of Warfarin for International Normalized Ratio Target 2.0 to 3.0.

he number of patients on warfarin therapy is rising steadily. Although warfarin is beneficial, it carries a high risk of bleeding, especially if the international normalized ratio (INR) values exceed 3.0. Currently, no warfarin initiation regimens have been developed for the Asian population, especially for Malaysians. This article describes the efficacy and safety of a new initiation regimen for warfarin among warfarin-naive patients. Data were retrospectively collected from the ambulatory and inpatient settings. A total of 165 patients who each had a target INR of 2.0 to 3.0 were included in the study. The mean age was 57.2 years and 94 patients were male. A total of 108 patients used Regimen 1 (5 mg/5 mg/3mg) and the rest of the patients used Regimen 2 (5 mg/3 mg/3 mg). Most patients used warfarin either for atrial fibrillation (52.1%) or for venous thromboembolism (29.7%). Overall, 88 of the patients had INR values above 50% from the baseline on Day 4. Additionally, 13 patients had INR values of >3.2, which required withholding and lower dose of warfarin. The predicted weekly maintenance warfarin dose (23 ± 0.5 mg/week) was found to have correlated closely with the actual maintenance dose (22.8 ± 0.5 mg/week; = 0.75). Nearly two thirds (70.3%) of the patients achieved the target INR on Day 11. The warfarin initiation regimens in this study was simple, safe, and suitable to be used in both ambulatory and inpatient settings for managing warfarin therapy.