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EXTENDING THE LIFE OF INSULIN PUMP INFUSION SETS BY REMOVAL OF PHENOLIC EXCIPIENTS FROM INSULIN INJECTION
Abstract
Background and Aims
Insulin pump wearers frequently experience the phenomenon of unexplained hyperglycemia or “site loss,” where injections have minimal effect and are thus “lost”. Site loss is typically observed between 48 and 72 hours of wear. We believe that one key reason for this lack of performance is the presence of toxic phenolic compounds in the insulin formulation, which are added in all commercially available insulin analogs as preservatives and stabilizers. Specifically, there are studies showing that exposure to phenolic excipients induces proinflammatory response and cell death, stimulating additional inflammatory processes, which decrease insulin efficacy overall. Therefore, insulin efficacy and infusion site longevity may be improved by removing phenolic excipients in the infusion set immediately before injecting into the body.
Methods
Phenolic excipients were removed from insulin in the cannula through electrochemical oxidization. As a proof of concept, we used a commercially available carbon screen printing electrode. We modified the electrode surface with bio-compatible polyelectrolyte to prevent passivation of the electrode and ensure the integrity of insulin.
Results
Our chronoamperometry results showed that current decay reduced from 91.4% to 46.8% on a polyelectrolyte modified electrode comparing to bare electrode, indicating an improved resistance to passivation. 32% phenol was removed from solution in one hour on a modified electrode, whereas only 4.4% phenol was removed on a bare electrode. HPLC data confirmed that insulin remained intact through electrochemical removal of phenols.
Conclusions
Electro-oxidization of phenolic compound on polyelectrolyte modified surfaces can remove these preservatives while maintaining the integrity of insulin.