Lithocholic‐acid‐containing poly(ester–anhydride)s

New degradable poly(ester‐anhydride)s were prepared by melt polycondensation of poly(sebacic acid) (PSA), transesterified by different amounts (30–90%) of lithocholic acid (LCA), a natural hydroxy bile acid. Transesterification of PSA is a one‐pot reaction that starts with a high‐molecular‐weight polymer based on anhydride bonds and yields polymer based on random anhydride–ester bonds. A systematic study of the synthesis, characterization, degradation in vitro , drug release, and stability of these polymers was performed. Polymers with molecular weights ( M w ) in the range of 12 000–115 000 and melting points in the range of 55–112 °C were obtained for 30–90% of lithocholic acid content. NMR and IR spectroscopic analyses indicate the formation of ester bonds in the polyanhydride backbone. The experimental results fit the calculated molecular weight, with the highest M w obtained for a 4:6 PSA–LCA ratio. The study shows that some of these new degradable copolymers can be potentially used as carriers for the controlled release of drugs. Copyright © 2003 John Wiley & Sons, Ltd.