Dimethylsilanediol from silicone elastomers: Analysis, release from biopharmaceutical process equipment, and clearance studies

Polysiloxanes are considered one of the most important commercial families of synthetic elastomers. They are frequently employed in biopharmaceutical manufacturing equipment as flexible single-use solutions due to superior material properties and compatibility with diverse sterilization methods. Extractables and leachables (E&L) testing is essential in qualifying such equipment, involving extraction studies to assess the potential release of compounds from plastic components for risk assessment. Silicone releases oligomeric siloxanes and small hydrolysis products, with dimethylsilanediol (DMSD) being the main hydrolysis product found in significant concentrations in aqueous process solutions. DMSD presents challenges for analysis, requiring specifically tailored analytical methods to detect it, which are commonly not applied in standard E&L screening tests. In biopharmaceutical manufacturing, it is relevant to consider the potential of DMSD to repolymerize into silicone oil when specific process parameters are altered. This may lead to interactions with drug ingredients, including proteins, resulting in the formation of aggregates. We synthesized and characterized DMSD using X-ray structure analysis and established an HPLC method with a refractive index detector to investigate the release of DMSD from commercially available silicone tubing used in drug manufacturing following autoclaving and irradiation. Subsequently, we assessed typical biopharmaceutical downstream operations for effectively removing this compound from the process stream.