PB0323 - Neutralization of varying sources of heparin using protamine sulfate and a novel synthetic peptide

Background: Heparin is a widely used anticoagulant that is generally administered intravenously in a clinical setting. In the case of over-administration, it is neutralized using protamine sulfate, which is the only available pharmaceutical for this purpose.

Aims: The aim of this study was to investigate the reversal effect of a commercially available 3.12 kDa peptide and compare its strength of reversal to protamine.

Methods: Normal citrated plasma was obtained from Loyola University Medical Center blood bank and pooled. Aliquots of plasma were supplemented with bovine, porcine, and ovine heparins ranging in concentrations from 0 to 2.50 µg/mL. Samples of plasma were also treated with saline, 2.50 µg/mL of protamine sulfate, or 2.50 µg/mL of the peptide. Concentrations of thrombin were measured over the course of 90 minutes in triplicate. Visualization of data was carried out using ggplot2 in R.

Results: Thrombin generation was noticeably increased in the presence of both protamine sulfate and the peptide, as expected. Over the range of concentrations of heparins tested, peak thrombin concentrations and endogenous thrombin potentials were significantly greater in the samples with neutralized heparin compared to samples with saline alone for all heparins (figures 1a-c. and 2a-c.). The peptide seemed to generally show a lower potency to protamine but still had a significant reversal effect. Interestingly, there seemed to be a slight hormetic effect on peak thrombin concentrations, however this would need to be statistically demonstrated by modeling.

Conclusion(s): The reversal effect of this peptide, in vitro, shows promising results compared to protamine sulfate. Adjusting concentrations of this peptide for potency may prove to perform similarly as protamine sulfate and provide a possible alternative for heparin neutralization. Studies mathematically modeling responses of clotting parameters are in the works to produce a more robust analysis of the reversal capabilities of this peptide.