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A. A. Dias, B. Plum, A. Petit, J. Lebouille, S. Braak, T. Handels, S. vander Wal; Biodegradable Polyurethane (meth)acrylate Microparticles as Controlled Drug Delivery System for the Eye. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1821.
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Crosslinked microparticles (MPs) offer the opportunity to control degradation and drug release by varying crosslink density and composition. One route to produce crosslinked materials is the use of photopolymers. Photopolymers have been used in dentistry and ophthalmology . An obstacle to the use of biodegradable materials is the acidity caused by hydrolysis of the polyester backbone that leads to instability of the encapsulated compounds as well as inflammatory host responses.Long-term controlled release has been achieved with non degradable systems, however most degradable systems in development face challenges of controlled degradation and associated acidity. The purpose of this study was to prepare photocrosslinked MPs based on biodegradable urethane (meth)acrylate oligomers that show a reduced pH effect upon degradation. As well as this to investigate the release profile of dexamethasone, a potent drug to treat macular edema.
Biodegradable urethane (meth)acrylate polyester oligomers were synthesized. These oligomer building blocks were photocrosslinked in suspension to produce MPs. The photocrosslinked polymers were degraded hydrolytically and monitored by weight loss and pH measurements. Drug release was determined with dexamethasone as the test drug
Degradation ranging from 30 days to > 200 days was observed. Notably degradation was not accompanied by the pH drop/ acidity that is typical of biodegradable polymers.Release studies with dexamethasone from MP (10mg) ranging from 60 -120 micron revealed a zero order release of 7 uG /day
This study shows that tailoring the building blocks of oligomers used to prepare polyurethane (meth)acrylate MPs offers a great potential to develop a a new class of biodegradable ocular drug delivery systems.
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