Synthesis, characterization and in vitro degradation of a new family of alternate poly(ester-anhydrides) based on aliphatic and aromatic diacids

A new family of alternate poly(ester-anhydrides) containing aliphatic and a romatic diacids were synthesized. The dicarboxylic acids were obtained by d erivatization of p-hydroxy benzoic acid at the hydroxy terminus with cyclic anhydride (adipic anhydride and succinic anhydride) and subsequently polym erized via the corresponding mixed anhydrides by melt polycondensation. DSC traces revealed that the polymers had low T-g (<40<degrees>C) and no cryst allinity. The static contact angle measurements indicated that the poly(est er-anhydrides) were more hydrophobic than poly(D,L-lactide) and poly(adipic anhydride). In vitro degradation of the polymers was also investigated in pH 7.4 PBS at 37 degreesC. It was found that degradation rate of the poly(e ster-anhydrides) increased with p-carboxy phenyl adipic monoester (CPA) con tent in the polymers and the degradation duration could be adjusted from ca . 20 days to ca. 2 months. Erosion curve of poly(p-carboxy phenyl adipic mo noester anhydride) (PCPA) was characterized by a linear region of weight lo ss at nearly constant rate in the first 7 days (ca. 80% of weight loss) fol lowed by a gradual decrease region. IR and SEM analysis showed that signifi cant erosion of PCPA occurred in the outer layer and no apparent erosion co uld be seen in the inner layer of the degrading sample after 7-day degradat ion. The poly(ester-anhydrides) may be used as either anti-infective polyme ric prodrugs or matrices for drug delivery. (C) 2000 Elsevier Science Ltd. All rights reserved.