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Vanessa Andres-Guerrero, Mengmeng Zong, George Mihov, Aylvin Dias, Rocio Herrero-Vanrell; Dexamethasone Sustained Delivery From Polyesteramide Microspheres For Intraocular Administration. Influence Of Sterilization. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5054.
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© ARVO (1962-2015); The Authors (2016-present)
Amino acid based polyesteramides (PEAs) are a new family of biodegradable polymeric materials based on α-amino acids, aliphatic dicarboxylic acids and aliphatic α-ω diols. The aim of the current study was to determine the effect of a sterilization dose of γ-irradiation (25kGy) on the release profile of dexamethasone (DX)-loaded PEA microspheres (Ms), to evaluate the use of these systems as carriers for controlled intraocular drug delivery.
DX-loaded Ms were prepared following an emulsion-solvent evaporation technique. Ms were characterized by particle size (dynamic light scattering), morphology (scanning electron microscopy) and DX-encapsulation efficiency. In vitro release studies were carried out for 24 days by suspending the Ms (5mg) in 1.5ml of PBS (pH 7.4, 37C) isotonized with NaCl. At pre-set times (1h, 24h and twice a week for 24 days) the release medium was collected and DX levels were quantified by HPLC. Freeze-dried DX-loaded Ms were sterilized with a 60Co radiation source (25 kGy). Sterilized Ms were characterized following the same procedures described above.
PEA Ms were spherical and had smooth surface with sizes ranging between 20-40 µm in all cases. The encapsulation efficiency was 85.14±0.99% for non-sterilized DX- Ms and 85.28±0.81% for sterilized DX-Ms (180.99±2.39 µg DX/mg Ms and 181.57±2.76 µg DX/mg Ms, respectively). The DX release profile of non-sterilized Ms had an initial burst of 17.69±0.58 µg DX/mg Ms released in the first 24 h, similar to the one obtained for sterilized Ms (17.28±0.44 µg DX/mg Ms). A progressive sustained release of DX was observed for the following days. At day 24, the cumulative release of DX was 80.86±2.40 µg DX/mg Ms for non-sterilized Ms and 79.45±4.74 µg DX/mg Ms for sterilized Ms (45.27±1.11% and 43.80±3.28% of the encapsulated DX, respectively).
PEA Ms developed are capable of providing a sustained release of DX for at least 24 days. Non significant differences were found between sterilized and non-sterilized MS. Gamma-radiation had no significant effect on the release profile of the microspheres. Biodegradable PEA Ms are potentially useful to develop new controlled drug delivery systems for treating ophthalmic diseases affecting the back of the eye.
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