An Investigation to Examine the Effect of the Elastomeric Surface Treatment on Protein Stability

Various kinds of treatments on the surface of the elastomeric components can have negative impacts on the quality of protein therapeutics. We compared the effects of bare (non-siliconized and nonlaminated), siliconized, and fluoropolymer-laminated elastomeric components on the stability of ß-lactoglobulin, human serum albumin, adalimumab, abatacept, and immunoglobulin antibodies. The study was conducted in two main parts. Part I was to evaluate the stability of proteins under agitation-induced stress. Protein aggregate formation, turbidity, and protein recovery were analyzed using dynamic FI, absorbance at 350 nm, and size-exclusion high-performance liquid chromatography, respectively. Proteins were found to be more stable with laminated stoppers as compared with bare or siliconized stoppers. Part II was to identify the chemical modifications when the proteins were stored in contact with the same three stoppers. Capillary isoelectric focusing analysis of the adalimumab samples showed formation of acidic variants in siliconized and bare stoppers. Reverse-phase high-performance liquid chromatography suggested chemical changes to the human serum albumin. Analysis of tryptic digest of human serum albumin by liquid chromatography/mass spectrometry/mass spectrometry indicated that the amino acids most susceptible to oxidation (cysteine, tryptophan, and methionine) were also the ones that were modified. Part III of this study investigated the barrier property of the fluoropolymer film with no drug product. Our results were consistent with the suggestion that the fluoropolymer lamination provides a barrier that prevents leachables from the elastomeric components into the protein therapeutics. Our work provided an in-depth understanding of the effects of elastomeric surface treatments on the biophysical and chemical stability of protein drugs.