Degradation and drug delivery properties of poly(1,4-cyclohexanedicarboxylic anhydride)

Polyanhydrides for drug-controlled release systems from cis- and trans-1,4-cyclohexanedicarboxylic acid (1,4-CHDA) were synthesized by melt polycondensation. The degradation of polymers was estimated by weight loss in 0.1 mol l(-1), pH 7.4 phosphate buffer at 37 degrees C. The drug delivery was conducted in the same buffer. The results show that the different polymers lost weight over 150-360 h, and fine surface erosion was investigated. The different conformation of CHDA has an obvious influence on the degradation of polyanhydrides due to their different crystallinity, with higher crystallinity samples degrading much more slowly. The incorporation of adipic acids into the poly(CHDA) can obviously accelerate the degradation and the introduction of -CH2- segments increased the flexibility of polyanhydride backbone and accelerated the degradation rate. In vitro delivery experiments show that Bruffen was completely released in about 10 days from a melting mold disk with a fine linear delivery curve.