Stability of DL-poly(lactic acid) in aqueous solutions

DL-poly(lactic acid) of molecular weight about 2500 was prepared by polycondensation of lactic acid and characterized by viscosimetry, infrared spectroscopy, light scattering, GPC, and NMR. Tablets made of the above polymer were immersed in buffer solutions at 37degreesC, and their swelling behavior was recorded as a function of time, in terms of weight gain. In the same experiments, the hydrolytic stability of PLA was assessed by measuring the weight loss after drying the tablets. To inhibit any degradation due to bacteria, formaldehyde was added to the solution as a biostatic factor. (C) 2002 Wiley Periodicals, Inc.