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Because leaching of extractable substances into pressurized formulations should be minimized, valve materials and other components that are in contact with the product meet the requirements under Elastomeric Closures for Injections 381 (Note that under Physicochemical Test Procedures in 381 the directions for preparing a sample require pre-extraction, which may cause an underestimate of the amount of extractables from a given component.) See also Aerosols under Pharmaceutical Dosage Forms 1151.