Results and Discussion: As anticipated, the binding affinity of antidotes to UFH decreased with increase in salt content in the buffer solution (Figure 1).ĭebye-huckel plot of association constant versus salt concentration showed linear relationship for both N-UHRA and PS. Activated partial thromboplastin time assay (aPTT) was performed in human platelet poor plasma (PPP) and anticoagulated human PPP respectively to assess biocompatibility and neutralization capability of antidotes. We titrated UHRA, N-UHRA and PS against UFH at varying salt concentrations. ITC experiments were performed on VP-ITC microcalorimeter. We synthesized UHRA with no mPEG chains (N-UHRA) to evaluate its crucial role in the design of UHRA. Methods: UHRA was synthesized by anionic ring opening polymerization of glycidol and mPEG, post-modified with multifunctional tertiary amines to generate cationic groups (Figure 1). In this study, we use ITC to demonstrate the structural superiority of UHRA in comparison to PS. We hypothesize that the presence, density and length of mPEG chains in UHRA is crucial to attain maximum efficacy and minimal toxicity. This raises an important question: why UHRA is an efficient heparin antidote with minimal non-specific protein binding, while PS fails to reverse the anticoagulation effects of LMWHs and fondaparinux and binds to proteins in competitive media such as human blood. Using Isothermal titration calorimetry (ITC), we observed that both PS and UHRA bind to UFH, LMWHs and fondaparinux with micromolar dissociation constant. UHRA has three components: hyperbranched polyglycerol core comprising heparin binding groups and methoxy polyethylene glycol (mPEG) chains emanating from the core. Understanding this clinical need, we developed a Universal Heparin Reversal Agent (UHRA) capable of reversing anticoagulation of all clinically available parenteral anticoagulants. However, PS partially neutralizes anticoagulation of low molecular weight heparins (LMWHs) and is ineffective against fondaparinux. PS electrostatically interacts with heparins to generate complexes devoid of anticoagulation. Protamine sulphate (PS), a cationic peptide is used to reverse unfractionated heparins (UFH). University of British Columbia, Chemistry, Canadaīackground and Objective: To avert haemorrhage associated with heparin therapy, antidotes are required. University of British Columbia, Department of Chemical and Biological Engineering, Canada University of British Columbia, Pathology and laboratory Medicine, Canada

Antidote for heparin