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S. P. Patel, G. Mishra, V. M. Tamboli, A. K. Mitra; Development of Dexamethasone Loaded Nanoparticles Utilizing Various Combination of Triblock Polymer for the Treatment of Retinal Diseases. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5313.
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To determine the effect of hydrophobicity and molecular weight of polymer on release profile of dexamethasone for the treatment of macula edema.
Nanoparticles were prepared by single emulsification method utilizing various compositions of triblock polymer such as PLA-PEG-PLA and PCL-PEG-PCL. Briefly 100 mg of polymer and 10 mg dexamethasone were dissolved in methylene chloride. The resulting oil phase was emulsified in 2.0 % aqueous solution of polyvinyl alcohol (PVA) with the help of a tip sonicator at 60 W for 5 min to form oil in water (o/w) emulsion. The resulting organic solvent was evaporated under vacuum to form nanoparticles. The unreacted drug and PVA residue were washed 3 times with DI water and the nanoparticles were collected by ultracentrifugation at 21,000 RPM for 1 h. Drug entrapment efficiency was determined by HPLC using C-18 reverse-phase column at 254 nm. Particle size was characterized by DLS (dynamic light scattering) and SEM (scanning electron microscopy). In vitro release study was performed using dialysis method in phosphate buffer saline at pH 7.4.
Drug entrapment efficiency was found to be highest (50-60 %) in case of PCL-PEG-PCL and increases with molecular weight of polycaprolactone. Morphologic observation of nanoparticles loaded with dexamethasone demonstrated uniform, rounded particles of 200-300 nm. The release of dexamethasone was sustained over 2 weeks in polycaprolactone based nanoparticles due to slow degradation of polycaprolactone.
Nanoparticles of polycaprolactone based triblock polymer showed better entrapment and release profile than polylactide based polymer. So nanoparticles of polycaprolactone based triblock polymer could be a promising tool for sustained ocular drug delivery.
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