The effects of ultrasound irradiation on a biodegradable 50–50% copolymer of polylactic and polyglycolic acids

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Abstract
The aim of this study was to investigate the effects of ultrasound irradiation on a biodegradable drug delivery system. Microporous, disk-shaped specimens of a 50-50% copolymer of polylactic and polyglycolic acids were gel cast from an acetone solution. A protein was incorporated in these specimens, which were then immersed in phosphate buffered saline and subjected to ultrasound irradiation every second day. The investigation was performed in two phases: in the first, a study was performed for 58 days to determine if ultrasonic irradiation affected the kinetics of protein release from the specimens. In the second phase, effects of frequency and duration of the ultrasound signal on the degradation of the implant were studied for 40 days. The results indicate that ultrasound irradiation resulted in almost a threefold increase in protein elution from the specimens. Both the ultrasound frequency and signal duration affected the molecular weight loss and mass loss, and changed the overall degradation kinetics of the polymer. © 1994 John Wiley & Sons, Inc.
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