Synthesis and Degradation Characteristics of Polyurethanes Containing AZO Derivatives of 5-Amino Salicylic Acid

摘要

New types of biodegradable and pH sensitive polyurethanes containing azo derivatives of 5-aminosalicylic acid (5-ASA) were synthesized by condensation of hexamethylene diisocyanate (HDI) with 4,4'-dihydroxy azobenzene-3,3'-dicarboxylic acid (AZO I) or 4,4'-dihydroxy 3'-formyl azoben-zene-3-carboxylic acid (AZO II).They contained both hydrolysable urethane bonds and enzymatically degradable azo-aromatic links.Degradation of polyurethanes (PU-AZO I and PU-AZO II) in phosphate buffer solutions was pH dependant.In basic conditions AZO I or AZO II was rapidly released over 48 h.Incubation of PU-AZO I and PU-AZO II with rat cecal contents at 37 deg C gradually released 5-ASA,and the amount of drug released was 85% and 78% in 48 h respectively.These polyurethane derivatives are being investigated for colon-specific drug delivery systems for treating inflammatory bowel disease based on the pH-dependant degradation of the polymer.