A reproducible rat model for warfarin studies: Prothrombin time assessment with minimal blood using the CoaguChek XS and determination of an effective warfarin dosag

Abstract

Warfarin research in rats is often challenged by methodological inconsistencies and large blood volume requirements. This study aimed to validate a refined, reproducible rat model for serial prothrombin time (PT) monitoring using the CoaguChek XS, in alignment with the 3R principles, and to determine an effective warfarin sodium dosage. Male Wistar albino rats received daily oral warfarin (0.125-0.750 mg/kg) for 5 days. PT was measured using the whole-blood CoaguChek XS and two laboratory plasma assays (Innovin, Thromborel S). Agreement was assessed using Bland-Altman and Passing-Bablok regression. The CoaguChek XS consistently yielded higher PT values than laboratory tests but showed strong agreement up to 25 seconds. A daily dose of 0.125 mg/kg resulted in a stable anticoagulant effect without mortality. Doses Doses of 0.250 mg/kg and higher were toxic, causing PT prolongation beyond the device's range and high mortality within 4-7 days after the initiation of treatment. In conclusion, the CoaguChek XS is a reliable tool for experiments requiring repeated measurements. Values remain reliable up to 25 s, and 0.125 mg/kg is a safe dose for short-term studies, effectively supporting animal welfare and the 3R principles.