Amino acid based polyesteramides (PEAs) are a new generation of biodegradable polymeric materials based on a-amino acids, aliphatic dicarboxylic acids and aliphatic a-? diols. Dexamethasone (DX) is a glucocorticoid widely used in ophthalmology to prevent and/or treat several ocular diseases. The aim of this study was to evaluate the suitability of PEA microspheres (Ms) to be used as carriers of DX for controlled delivery in ophthalmology. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/31758_hollandite_structure_figure.jpg' alt='' />Unloaded and DX-loaded PEA Ms were prepared following an emulsion-solvent evaporation technique. Ms were characterized by particle size, morphology and DX-encapsulation efficiency. In vitro release studies were carried out for 90 days by suspending the Ms in isotonized PBS. PEA Ms were sterilized with 60Co radiation source (25 kGy) and then characterized. To determine the toxicity of unloaded PEA Ms, a screening study (0.125-1 mg Ms) was performed in an organotypic culture system of wild type rats' retinas, by TUNEL assay and conventional histology in short and long term cultures (7 and 20 days in culture, respectively). Toxicity of sterilized DX-loaded PEA Ms was tested in the same system with 0.625 mg of Ms.The encapsulation efficiency of DX was around 85% (181.57�2.76 �g DX/mg Ms) and the release profile of DX had an initial burst of 17.28�0.44 �g DX/mg Ms in the first 24 h. The cumulative release of DX after 90 days was 98.43�9.65 �g DX/mg Ms (54.10�6.21%). Sterilized DX-loaded PEA Ms did not show any difference with non-sterilized Ms in terms of particle size, morphology, encapsulation efficiency and release profile of DX up to 90 days. Retinas treated with unloaded and DX-loaded PEA Ms did not show signs of toxicity in organotypic retinal cultures up to 0.625 mg.Biodegradable PEA Ms are potentially useful to develop new controlled drug delivery systems for treating ophthalmic diseases affecting the back of the eye.

Biodegradable polyesteramide microspheres for controlled drug delivery in ophthalmology

247th National Meeting (2014)

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