Changes in prothrombin time and activated partial thromboplastin time when administrating dabigatran, a direct inhibitor of thrombin

Abstract

We examined the availability of prothrombin time (PT) and activated partial thromboplastin time (APTT) for monitoring the anticoagulant effects of dabigatranetexilate, a direct inhibitor of thrombin. We measured PT and APTT of 10 healthy volunteers before and after taking dabigatran (150 mg twice daily) using some reagents. In the comparison of APTT results, we used three units: number of seconds, APTT prolonged ratio, and APTT ratio. To determine APTT prolonged ratio, we divided the number of APTT seconds after the administration of dabigatran by the number of APTT seconds before administration. On the other hand, APTT ratio is obtained by dividing the number of APTT seconds of each subject by that of normal plasma. Our test results suggest that APTT is more useful for monitoring the anticoagulation effect of dabigatran. When we assess these results, differences in the unit of APTT prolonged ratio between reagents are smaller than those in unit of seconds. However, it is cumbersome to determine the APTT prolonged ratio of respective patients. Thus, we assessed the APTT ratio as a solution, and then obtained the equivalent outcome to the APTT prolonged ratio. In general, we measure APTT in seconds to monitor the anticoagulation effect of dabigatran. However, it is suggested that the APTT prolonged ratio can help correct the differences in APTT results between reagents (facilities).