Effect of geometry on the erosion characteristics of polyanhydride matrices

The aim of this study was to investigate the effect of device geometry on the erosion characteristics of poly[1,3-bis(p-carboxyphenoxy) propane:sebacic acid], p(CPP:SA), matrices in phosphate buffer to obtain an insight into the mechanism of polyanhydride erosion. Matrices with different dimensions were prepared using a melt moulding technique and erosion was followed by determining changes in polymer molecular weight, water absorption, mass loss and release of monomers with time of immersion in phosphate buffer pH 7.4 at 37 degrees C. In all matrices the erosion process was characterised by an initial lag phase during which there was a rapid decrease of polymer molecular weight but no significant water absorption, mass loss or release of monomers. The rates of absorption of water and loss of mass after the lag period showed characteristics of both surface and bulk eroding systems. (C) 1998 Elsevier Science B.V.