Phenolic Preservative Removal from Commercial Insulin Formulations Reduces Tissue Inflammation while Maintaining Euglycemia

Abstract

Background: Exogenous insulin therapy requires stabilization of the insulin molecule, which is achieved through the use of excipients (e.g., phenolic preservatives (PP)) that provide protein stability, sterility and prolong insulin shelf life. However, our laboratory recently reported that PP, (e.g., m-creosol and phenol) are also cytotoxic, inducing inflammation and fibrosis. Optimizing PP levels through filtration would balance the need for insulin preservation with PP-induced inflammation. Method: Zeolite Y (Z-Y), a size-exclusion-based resin, was employed to remove PP from commercial insulin formulations (Humalog) before infusion. Results: PP removal significantly decreased cell toxicity in vitro and inflammation in vivo. Infusion site histological analysis after a 3 day study demonstrated that leukocyte accumulation increased with nonfiltered preparations but decreased after filtration. Additional studies demonstrated that a Z-Y fabricated filter effectively removed excess PP such that the filtered insulin solution achieved equivalent glycemic control in diabetic mice when compared to nonfiltered insulin. Conclusion: This approach represents the proof of concept that using Z-Y for in-line PP removal assists in lowering inflammation at the site of insulin infusion and thus could lead to extending the functional lifespan of insulin infusion sets in vivo.

In Vivo Study of the Inflammatory Tissue Response Surrounding a Novel Extended-Wear Kink-Resistant Insulin Infusion Set Prototype Compared With a Commercial Control Over Two Weeks of Wear Time

“…5,23,24 The inflammatory process changes dynamically over wear time due to ongoing tissue trauma caused by the cannula and proinflammatory insulin and insulin preservatives (eg, m-Cresol). 6,7,25,26 The evidence of the impact of preservatives on the inflammatory tissue response is conflicting, as it has been shown that a decrease of preservatives is associated with the formation of insulin aggregates (fibrils) which are known to increase inflammation. [27][28][29] In contrast, a recent well-designed IIS study in diabetic swine concluded that the insulin molecule itself is the major pro-inflammatory agent when infused into the SC tissue, rather than the excipients.…”

New insight into the importance of formulation variables on parenteral growth hormone preparations: potential effect on the injection-site pain

“…More research is needed towards the development of buffer-free and preservative-free formulations. It has been recently suggested that the removal of phenolic preservatives from the commercially available insulin products before SC injection by using Z-Y filtration reduces the inflammatory reactions induced by repeated SC injections ( 146 , 147 ). Finally, alternative buffers and preservatives should be explored and studied for use in the development of future formulations.…”

Diabetes and its Complications

“… Their Review ingeniously combines information from cell, animal, and clinical studies to explain the multifaceted pharmacology of metformin. Mulka et al contributed a research article on improving the safety of commercial insulin formulations . The authors found that after removal of the phenolic preservative, tissue inflammation was reduced without loss of efficacy.…”

“…Mulka et al contributed a research article on improving the safety of commercial insulin formulations. 6 The authors found that after removal of the phenolic preservative, tissue inflammation was reduced without loss of efficacy.…”