A CHROMOGENIC METHOD FOR QUANTITATION OF DIRECT THROMBIN INHIBITORS: A CASE STUDY

Abstract number: P-S-127

Castellone¹ D.D., Peerschke² E.E.I.B.

¹¹Special Coagulation, New York Presbyterian Hospital Weill Cornell Medical Center ²²Pathology, Weill Cornell Medical Center, New York, United States

How-to-cite Castellone DD, Peerschke EEIB. A CHROMOGENIC METHOD FOR QUANTITATION OF DIRECT THROMBIN INHIBITORS: A CASE STUDY. J Thromb Haemost 2007; 5 Supplement 2: P-S-127

Abstract

Introduction: Background:

Direct Thrombin Inhibitors (DTIs) are potent anticoagulants used particularly in patients with Heparin Induced Thrombocytopenia/Thrombosis (HIT). Monitoring DTI therapy requires specialized assays, since the APTT is variably sensitive to therapeutic DTI levels, and is generally unable to reliably discriminate DTI concentrations >1ug/ml

Methods: We implemented a specific chromogenic anti factor IIa assay to monitor DTI therapy. In this assay, exogenous human thrombin (10 NIH U, Sigma) is neutralized in proportion to the amount of DTIs present in patient plasma. Remaining thrombin activity hydrolyzes a chromogenic substrate (S-2366, Chromogenix). Hydrolysis is quantified spectrophotometrically (405nm). DTI standards (0-1.6ug/ml) and controls (1.0 & 0.5ug/ml) are prepared using DTI stock solutions and pooled normal plasma. The assay was automated on the BCS (Dade/Behring).

This assay was used to monitor intraoperative bivalirudin levels in a patient with HIT during cardiopulmonary bypass. Anti IIa assays were performed in the Clinical Laboratory with a 10 - 15 min turn-around time. Activated Clotting Times (ACT) were performed simultaneously in the operating room.

Results: See Table

Table:

Time	Pre-op	T 20 min	T40 min	T60min	T 80 min	T 100min	T120 min	T140 min	T160 min
ACT (sec)		380	470	460	500	460	350	280	295
Bivalirud (ug/ml)	4.0	11.0	14.0	16.0	14.0	12.0	10.5	6.5	4.0

Conclusions: The chromogenic F IIa assay was used successfully to monitor bivalirudin levels during cardio-pulmonary bypass. The ACT lacked sensitivity to bivalirudin levels exceeding 4ug/ml. Additional studies are required to fully evaluate the clinical utility of the chromogenic anti F IIa assays for monitoring DTI therapy.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

Session Details

Date:	01/08/2007
Time:	00:00-00:00
Session name:	XXIst ISTH Congress
Subject:
Location:	Oxford, UK
Presentation type:
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