PB0551 - A comparison of USP Potency Adjusted and Mass Adjusted Heparins of Bovine, Ovine, and Porcine Origin in Various Assays

Background: Recently, the shortage of porcine mucosal heparin has prompted the resourcing of heparin from alternate sources including tissues from bovine and ovine origin. The heparins obtained from ovine origin exhibit comparable potency to porcine (190-210 U/mg), whereas heparins obtained from bovine origin exhibit considerably less potency (120-140 U/mg). The current potency assay is based on the inhibition of factor Xa utilizing a chromogenic substrate-based method.

Aims: The purpose of this study is to compare these heparins at mass and USP potency-adjusted levels in various laboratory assays.

Methods: Bovine, ovine, and porcine heparins were obtained from commercial vendors. The USP Potency of these agents was evaluated using an amidolytic anti-Xa method. Potency adjustment was done by weighing proportionally higher amounts of bovine heparin to match the ovine and porcine heparins. All agents and their pooled versions were supplemented with normal human pooled plasma in graded concentrations of 10-0 ug/mL and 1-0 U/mL. Such assays as aPTT, anti-Xa, anti-IIa, and thrombin generation assay were carried out.

Results: The composite results on the comparison of these agents in both the adjusted potency and mass concentrations are shown in figure-1 and table-1. In the mass adjusted studies, the bovine heparin consistently showed weaker effects in the aPTT, anti-Xa, and anti-IIa assays. The USP potency adjusted heparins showed minimal differences amongst different heparin solutions. However, in the thrombin generation assays, the potency adjusted heparins showed wider differences among different heparins and the bovine heparin showed stronger thrombin generation inhibitory potential.

Conclusion(s): These results show that heparins from different species can be potency-adjusted to exhibit comparable functional anticoagulant and antiprotease effects. However, in the thrombin generation inhibitory assay, the mass adjusted heparins show comparable results in contrast to the USP adjusted heparins, which may be due to the contribution of non-AT binding chain components that independently inhibit thrombin generation.