Pendent chain linked delivery systems: from concept to practice

Release of active ingredients from pendent chain linked hydrogels involves penetration of the medium, hydrolysis of the pendent link and diffusion of the active ingredient. Such systems would find practical applications only when the hydrolysis takes place at pH/spl sime/7. This was achieved by (a) using poly(N-vinyl imidazole) (PNVIm) as an enzyme mimicking polymer and (b) by incorporating imidazole groups in the vicinity of the ester link to be hydrolysed. These hydrogels would also serve as pH sensitive delivery systems.