A Novel Method to Assess Platelet Inhibition by Eptifibatide with Thrombelastograph®

We examined a novel method to detect platelet inhibition with thrombelastography (TEG®). We hypothesized that this method would be suitable for monitoring the antiplatelet effects of eptifibatide (Integrilin®). Whole blood from healthy volunteers was anticoagulated with 3.2% citrate or unfractionated heparin (7 IU/mL). For the platelet aggregation test, both citrate and heparinized samples were spiked with increasing concentrations of eptifibatide (0, 0.2, 0.4, 0.8, 1.6, and 4 &mgr;g/mL). Conventional kaolin TEG® was performed with citrated samples, and batroxobin-modified TEG® was performed with heparinized samples, which were spiked with eptifibatide at concentrations of 0, 0.4, 0.8, 1.6, 4, 8, and 24 &mgr;g/mL. Adenosine 5′-diphosphate-induced platelet aggregation was reduced to 6.4% ± 2.9% (citrate) and 10.3% ± 4.8% (heparin) with eptifibatide at the concentration of 4 &mgr;g/mL. The kaolin TEG® showed a decrease in maximum amplitude (MA) only at the eptifibatide concentration of 24 &mgr;g/mL and no change in &agr; angle, whereas with the batroxobin-based TEG®, the difference in MA and &agr; angle was observed at concentrations ≥0.8 &mgr;g/mL. Additionally, the time to achieve maximum MA was much shorter for batroxobin TEG® than for kaolin TEG®. We conclude that the batroxobin-modified TEG® is a sensitive method that detects platelet inhibition induced by eptifibatide.