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Kishore CHOLKAR, Sudharshan Hariharan, Rajyalakshmi Earla, Sriram Gunda, Ashim K. Mitra; Topical Delivery Of Dexamethasone Mixed Nanomicellar Formulation To The Posterior Segment: Formulation Development, Optimization And In Vivo Ocular Tissue Distribution. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3214.
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The objective of this study was to develop a stable mixed nanomicellar formulation, optimization and characterization. Also, determine the ocular tissue distribution upon topical drop administration in Male New Zealand albino rabbits.
Vitamin E TPGS and octoxynol-40, USFDA approved non-ionic surfactants, are used in different ratios to obtain an optimized formulation. Dexamethasone is a steroid, hydrophobic drug. It is the drug of choice for the treatment of posterior uveitis. Its solubility was improved with the development of this novel mixed nanomicelle formulation to get an overall concentration of 1 mg/mL. The novel mixed nanomicelle formulation was prepared by solvent evaporation technique. The optimized formulation was characterized for its improvement in drug solubulization efficiency, osmolality and micelle stability. Drug ocular bioavailability studies/tissue distribution studies were conducted in male New Zealand rabbits by topical drop administration. Liquid-liquid extraction was used for the extraction of dexamethasone from the homogenized tissues. Extracted drug analyzed using LC-MS/MS.
The optimized formulation showed a effective micelle size of about 18 nm with encapsulation ratio percentage > 95%. Drug entrapment was confirmed by NMR spectroscopy, the clarity of the formulation was determined by UV spectroscopy, thermal stability and regeneration time of obtimized mixed nanomicelle formulation was found to be above point of detection (90° C). Long term storage and stability studies of the formulation at 40° C, room temperature and at 4° C showed improved stability. Therapeutical drug concentrations, 50 ng/gm tissue, were observed in retina-choroid.
A clear mixed nanomicelle formulation was prepared and optimized. The novel mixed nano micellar formulation had shown increase in the drug solubility with good entrapment. The smaller size, lower poly dispersity index and improved stability of the formulation were observed. The formulation has shown improved stability for a longer period of time. Therapeutic levels of drug were observed in the posterior segment of eye (retina-choroid) after topical administration.
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