HEMA-based methacrylic carriers incorporating ketoprofen: chain flexibility and swelling behaviour

The chain flexibility, swelling and release behaviour of several copolymer systems of pharmacological interest have been studied. The systems are copolymers of 2-hydroxyethyl methacrylate with two support comonomers, i.e. N-(4-hydroxyphenyl) methacrylamide and N-[4-(2-hydroxy)ethoxyphenyl] methacrylamide and copolymers of 2-hydroxyethyl methacrylate with these carrier structures bearing ketoprofen (N-(4-[2-(3-benzoylphenyl)propionyloxy]phenyl methacrylamide and N-(4-[2-(3-benzoylphenyl)propionyloxy]2-ethoxyphenyl methacrylamide). In these copolymers ketoprofen was attached via different spacer groups, i.e. 4-aminophenoxy and 4-aminoethoxyphenyl. The chain structures are discussed on the basis of reactivity ratios. The properties of the polymeric drugs and of the parent carriers were studied comparatively by DSC and through the swelling of films from DMF solutions in pH 7.4 buffers. Data are discussed in terms of chain flexibility and swelling.