MRI investigation of hydration and heterogeneous degradation of aliphatic polyesters derived from lactic and glycolic acids: a controlled drug delivery device

Magnetic Resonance Imaging experiments have been used to investigate the de gradation of drug-loaded poly(glycolic lactic acid) (PGLA) 50:50 cylinders. Spatial variation in the rate of degradation throughout the polymer cross- section has been observed non-invasively using quantitative imaging of pene trant concentration, T-2 and self-diffusion coefficient. This spatial varia tion in the rate of degradation was attributed to the quicker degradation i n the inner region of the sample due to autocatalysis by carboxyl end group s generated upon ester bond cleavage. (C) 2001 Elsevier Science Inc. All ri ghts reserved.