• The ICH Q3C(R9) “Guideline for Residual Solvents” was revised using the ICH Minor Revision Procedure and reached Step 4 of the ICH Process on 24 January 2024.The document adopts a minor revision to section 3.4. concerning the consideration of solvent volatility for analytical methods.

    The Q3C ICH Guideline was finalised under Step 4 in July 1997 and provides recommendations on using of less toxic solvents in the manufacture of drug substances and dosage forms, as well as setting pharmaceutical limits for residual solvents (organic volatile impurities) in drug products.

    As part of the maintenance process, the Q3C Guideline incorporated the revision and inclusion of new Permitted Daily Exposure (PDE) levels as new toxicological data for solvents became available.

    In section 3.4 the guideline states that: “If only Class 3 solvents are present, a non-specific method such as loss on drying may be used, if the method is properly validated. The impact of solvent volatility on the test method should be considered in the validation.

    Validation of methods for residual solvents should conform to the current version of ICH guideline Q2 on Validation of Analytical Procedures”.


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