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Jesse T McCann, Yale Fisher, Szilard Kiss, Samuel Nemiroff; Dissecting the Intravitreal Injection: The Role of Silicones. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4174. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Poly(dimethylsiloxane) polymers (commonly known as silicone oil) are ubiquitous in medical equipment manufacture, and are used as a lubricant, stabilizer, and industrial adjuvant. Histologic analysis of injection sites in insulin-dependent patients with diabetes mellitus has shown multiple inflammatory granules in the areas of subcutaneous insulin injection. Interval intravitreal anti-VEGF has now become standard of care for chronic eye conditions. The persistance of silicone oil in eyes after multiple intravitreal injections has been observed by slit lamp biomicroscopy and confirmed by B-scan ultrasonography. This study will identify and quantify the components of ejecta from model systems simulating the intravitreal injection.
Syringes from multiple manufacturers were first flushed with toluene, balanced salt solution, and deionized water in order to isolate the small molecule components in the ejecta. The mixtures were then ejected into borosilicate glass vials for microscopic and spectroscopic analysis. 1-mL tuberculin syringes paired with 30-gauge needles from a variety of manufacturers were used to inject 0.05 mL aliquots of bevacizumab, ranibizumab, and vancomycin into borosilicate glass vials. The resultant ejecta were analyzed by electrospray ionization mass spectroscopy and transmission electron microscopy.
Mass spectroscopic evidence of poly(dimethylsiloxane) oligomers were found in all the sample were found in all samples subjected to electrospray ionization mass spectroscopy. The mass spectrographic fingerprints of all the samples were homologous, suggesting structural similarity between the lubricants used by syringe manufacturers. Higher concentrations of silicone oligomers were found when injecting large antibody drugs compared to deinoized water, suggesting that pharmaceutical excipients could have a role in the liberation of silicone lubricants from the syringe system.
Silicone lubricant is ubiquitous in the ejecta from disposable syringes in systems mimicking the conditions of intravitreal injection. This confirms observations by contact B-scan ultrasonography and slit lamp biomicroscopy. Excipient-drug interactions may play an important role in the pharmacokinetics of intravitreal large molecule (antibody) injections. Study of the interactions between anti-VEGF molecules and poly(dimethylsiloxane) oligomers is ongoing.
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