Evaluating Heparin Products for Heparin-Induced Thrombocytopenia Using Surface Plasmon Resonance

Heparin-induced thrombocytopenia (HIT) is an adverse immunological disorder caused by antibodies to platelet factor 4 (PF4)-heparin complexes. The analysis of HIT potential for different heparin and heparin-related products is important prior to their clinical application. Here, we report a rapid method for the evaluation of HIT potential of various heparin and heparin-related compounds using surface plasmon resonance (SPR). Solution competition between surface-immobilized heparin and soluble unfractionated heparin, low molecular weight heparin (LMWH), or ultra-LMWH binding to PF4 was performed using SPR to measure the half maximal inhibitory concentration (IC₅₀) of different heparin products. The IC₅₀ values of different unfractionated heparin active pharmaceutical ingredients (APIs) varied from 0.38 to 0.6 μg/mL and the IC₅₀ values of different LMWH APIs ranged from 2.4 to 2.9 μg/mL. The IC₅₀ of Arixtra® (a synthetic pentasaccharide ultra-LMWH) was not measurable even at very high concentrations. These differences in IC₅₀ values for different heparin products suggest a quantitative means for evaluating the HIT potential of various heparins and heparin-related products.