Abstract
Diseases affecting the posterior segment of the eye such as age-related macular degeneration and diabetic retinopathy are leading causes of blindness all over the world. The current treatment regimen for such diseases involves repeated intravitreal injections of anti- Vascular Endothelial Growth Factor (VEGF) proteins. This method is highly invasive and can lead to severe complications. In an attempt to develop less invasive alternatives, we propose the use of a controlled release system consisting of anti-VEGF loaded hollow microcapsules that can be administered periocularly to form drug eluting depots on the episcleral surface. The microcapsules with either positive or negative surface charge were prepared by a layer by layer approach and showed pH responsive permeability switching. An ex vivo experiment using porcine sclera indicated positively charged microcapsules remained on the episcleral surface over four days while the negatively charged microcapsules were washed away. These positively charged microcapsules were then loaded with anti-VEGF protein ranibizumab using pH dependent permeability switching and protein release from the microcapsules were studied using an in vitro setup. An ex vivo experiment utilizing porcine sclera demonstrated sustained release of ranibizumab over seven days with zero-order kinetics.
Highlights
Diseases affecting the posterior segment of the eye such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are leading causes of blindness all over the world
Optimal cutting temperature (OCT) compound was bought from Leica microsystems (Teban garden crescent, Singapore) and Vectorshield® mounting medium with DAPI was bought from Vector Laboratories (San Diego, CA, USA)
PSS doped CaCO3 microparticles were prepared to be used as templates to form the spherical hollow microcapsules. 2 mg/mL PSS was dissolved in 0.33 M CaCl2 and the solution was stirred using a magnetic stirrer for 10 min
Summary
Diseases affecting the posterior segment of the eye such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are leading causes of blindness all over the world. The current gold standard for treatment is intravitreal injection of anti-Vascular Endothelial Growth Factor (anti-VEGF) proteins and peptides, which directly delivers the drug into the vitreous humor. This technique overcomes various ocular barriers by directly delivering the drug at the site of action [3]. CMC is widely used as an emulsifying agent and thickener in pharmaceutical formulations This combination is expected to be biocompatible. In this study we utilize PRM and CMC to synthesize layer by layer assembled hollow capsules and evaluate their ability to act as anti-VEGF drug depots for treatment of AMD using the periocular route
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