The present invention relates to the use, as an agent for salting out an active substance in a composition for a dressing, of a copolymer of a salt of 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulphonic acid and the 2-hydroxyethyl ester of propenoic acid. It also relates to dressings of the type comprising at least one fatty substance and/or an elastomeric matrix and at least one active substance, which incorporate the aforementioned copolymer.
