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D. E. Babcock, IV, M. J. Burkstrand, R. A. Chappa, C. J. Hagemeier, L. G. Reddy, J. Slager, S. R. Erickson, T. M. Kloke; Injectable in situ Forming Ocular Drug Delivery System. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5312.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the feasibility of a novel injectable ocular drug delivery system.
Formulation studies were conducted with both protein and small molecule. Protein formulations were prepared by suspending spray-dried horseradish peroxidase (HRP) or Fab microspheres (diameter, ~5 micron) in a biodegradable polymer dissolved in biocompatible solvents. Triamcinolone acetonide (TA) formulations were prepared by mixing TA into the polymer solutions. Matrices were formed, without any chemical cross-linking agents, upon dispensing 50 microliters of the formulations into phosphate buffered saline (PBS), pH 7.4. In vitro elution was performed in PBS at 37°C, static. The physical and chemical stability of protein was evaluated by HPLC and the activity of the protein was determined by ELISA. In addition to the elution testing, matrix formation and injectability studies were performed in cadaveric eyes.
Protein formulations provided low burst with release rates of 2-10 mcg/day. Protein loads were sufficient for release up to 6 months. Release rates were shown to be tunable by adjusting formulation parameters. Formulations were injectable through 25 gauge or smaller needles and formed semi-solid to solid matrices in situ. TA formulations are currently being evaluated and results will be presented.
The in situ forming drug delivery system provides high drug load capacity with minimal burst, tunable elution control, and injectability through a 25 gauge needle.
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