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Ritesh Thekkedath, Koushik Barman, Shikha P Barman; OcuSurf: A Nanostructured, Membrane-Interactive, Biphasic Ocular Drug Delivery System for Once/Day Administration of Water-Insoluble Ophthalmic Medications. Invest. Ophthalmol. Vis. Sci. 2014;55(13):458.
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Most insoluble ophthalmic drugs are administered as eye-drop emulsions or suspensions for treatment of therapies such as those for keratitis, blepharitis, post-operative inflammation, glaucoma, dry eye, etc. Emulsions and suspensions can sometimes cause irritation at the ocular surface; long term use can lead to corneal damage and dry eye. Additionally, suspensions have lower drug absorption profiles, due to their rapid clearance before drug dissolution can occur. Design criteria for an ideal delivery system include ocular biocompatibility, ability to self-administer as eye-drops, enhancement of epithelial permeability and therapeutic duration. We have designed an eye-drop drug delivery system (OcuSurf) containing GRAS excipients, is membrane-interactive, demonstrates a melt transition at 37C and has molecular anisotropy that enables sustained drug release. Additionally, the formulation is stable at room temperature and can be manufactured to scale. Formulations were prepared with and without dexamethasone. We present formulation characterization by microscopy, melt transition, corneal permeability and in-vitro release data.
The formulation was prepared by mixing an organic drug-containing phase with an aqueous phase that formed a self-assembled structure with the organic phase. The formulation contained 0.1% w/w dexamethasone. Particle size distribution was measured using a Horiba LA-950. Both the drug-containing formulation and the vehicle were heated and melt transitions recorded. The delivery system was characterized under crossed polarizers, by an Olympus BX51P microscope.
The formulations were turbid, with a mean size of 0.8 microns. Both the formulations demonstrated unique anisotropy under polarized light microscopy, indicating self-assembly. The delivery systems demonstrated a “melt” transition at ~37°C, indicating that the formulation would “flow” evenly over the ocular surface. The flow properties of the formulations indicated its utility as an eye-drop dosage form. In-vitro release demonstrated sustained release of dexamethasone from the nanostructured system.
Sustained release of dexamethasone from a membrane-interactive eye-drop delivery system may result in a prolonged duration therapeutic effect.
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