A water based polymeric system is disclosed for PSA matrix for transdermalpatches comprising:a) an aqueous dispersion of a copolymer of a C1-C10 alkyl ester of an acrylicand amethacrylic acid in an amount of 10 to 50% by weight based on the totaldispersion weight, andb) a plasticizer,c) an active ingredient, wherein:cl ) said active ingredient acts also as a shrinkage reducing agent ableto reduce the shrinkage of the water PSA dispersion when spread ontoa surface to width values lower than 20 mm after 3 minutes rest, andc2) said active ingredient is an amount of 0.5% to 30% by weight basedon the dry copolymer weight.With this type of system, it is possible to prepare PSA adhesive matrix ofesterpolyacrylates without freeze drying and adding organic solvents. The presentinvention further relates to the process for preparing said water basedaqueouspolymeric and transdermal patches prepared therewith.
