Overcoming challenges in the chemical analyses of wound dressings: a practical approach based on solvent compatibility

International standards describing extractables and leachables (E&L) testing for chemical analyses are not prescriptive allowing much scope for interpretation. Balancing the requirements of regulatory agencies with issues of laboratory-based practicality and feasibility is challenging in the E&L analysis of advanced wound dressings, specifically the expectation of testing under 'exhaustive' conditions in three solvents (polar, semi-polar, non-polar) when not all of the test conditions/solvents are compatible with common wound dressing materials (e.g. silicone adhesives, polyurethanes). The aim of this study is to describe a rigorous E&L testing framework, aligning with the clinical usage of wound dressings whilst remaining strongly aligned with regulatory standards. Five major practical challenges were identified relating to the selection of suitable E&L solvents, including: selection of extraction conditions, inappropriate swelling, loss of device integrity, formation of particulates, and choice of appropriate analytical techniques. A systematic process was developed to identify acceptable/compatible solvents and justify the omission of solvents shown to be incompatible. A test case was developed to demonstrate how the framework can be adopted in support of real-life regulatory submissions. This systematic approach to design of E&L analysis of wound dressings may be useful in streamlining future regulatory submissions for medical devices including advanced wound dressings.