New biodegradable polyurethanes containing azo-linked polymeric prodrugs of 5-aminosalicylic acid (5-ASA) in the main chain were prepared by reacting 1,6-Hexamethylenediisocyanate (HDI) with 3,30-azobis(6-hydroxy benzoic acid) (ABHB) and 5-[4-(hydroxyl phenyl) azo] salicylic acid (HPAS) as azo derivatives of 5-ASA. The polymers were characterized by FTIR and 1H-NMR spectroscopy. The hydrolysis of polyurethane containing azoderivatives of 5-ASA was carried out in cellophane membrane dialysis bags containing aqueous buffer solution (pH 1/4 8.5 and pH 1/4 1) at 37 C. Detection of the hydrolysis product by UV spectroscopy showed that ABHB and HPAS were released by the hydrolysis of the urethane bond in the polymer chain.

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