Developing a Highly Active Blood Anticoagulant—a Heparin Complex with Glutamic Acid—by Simulating Chemical Equilibria Based on pH-Metric Data

Abstract

The anticoagulant activity of high-molecular-weight heparin is increased by developing a new highly active heparin complex with glutamate using the thermodynamic model of chemical equilibria based on pH-metric data. The anticoagulant activity of the developed complexes is estimated in the pH range of blood plasma according to the drop in the calculated equilibrium Ca²⁺ concentration associated with the formation of mixed ligand complexes of Ca²⁺ ions, heparin (Na₄hep), and glutamate (H₂Glu). A thermodynamic model is calculated by mathematically modelling chemical equilibria in the CaCl₂–Na₄hep–H₂Glu–H₂O–NaCl system in the pH range of 2.30 ≤ pH ≤ 10.50 in diluted saline that acts as a background electrolyte (0.154 М NaCl) at 37°C and initial concentrations of the main components of ν × 10⁻³ M, where n ≤ 4. The thermodynamic model is used to determine the main complex of the monomeric unit of heparin with glutamate (HhepGlu^5–) and the most stable mixed ligand complex of Ca²⁺ with heparin and glutamate (Ca₂hepGlu^2–) in the pH range of blood plasma (6.80 ≤ рН ≤ 7.40). It is concluded that the Ca₂hepGlu^2– complex reduces the Ca²⁺ concentration 107 times more than the Ca²⁺ complex with pure heparin. The anticoagulant effect of the developed HhepGlu^5– complex is confirmed in vitro and in vivo via coagulation tests on the blood plasma of laboratory rats. Additional antithrombotic properties of the developed complex are identified. The new highly active anticoagulant, HhepGlu^5– complex with additional antithrombotic properties, is patented.