Ocular drug delivery has seen several advances in the past few decades, with respect to new drugs, improved formulations, targeted delivery, as well as exploration of new routes of drug administration. New materials have been explored for encasing existing drugs, which can enhance treatment by increasing bioavailability, decreasing toxicity, providing better tissue adherence, targeted delivery as well as increased duration of action. The challenges and requirements are different for the anterior and posterior ocular segments. This review summarizes the recent advances in sustained ocular therapy, both to the anterior and posterior segments, which have been made possible, thanks to nanotechnology. We also discuss the distribution and fate of these nanocarriers themselves, postadministration, as well as clearance from ocular tissues.

The present study is aimed at the overall improvement in the efficacy, reduced toxicity and enhancement of therapeutic index of cisplatin. Solid lipid nanoparticulate delivery system of cisplatin has been developed by microemulsification method by using stearic acid, soy lecithin 95% and sodium glycolate. The formulations were then characterized with respect to size and its surface morphology, zeta potential, entrapment efficiency, in vitro drug release profile, in vivo drug targeting studies and its stability under specific conditions. The formulated solid lipid nanoparticles were oval with a diameter ranging from 250 nm to 500 nm. The lowest entrapment efficiency was found to be 47.59% and highest was found to be 74.53%. The zeta potential was in the range of -9.8 to -11.2 mv. In vitro release study was analyzed using various mathematical models. Highest cumulative percent drug release was observed with F-1 (97.22 %) and lowest with F-4 (78.43%) in 16 h. The in vivo result of formulated solid lipid nanoparticles of cisplatin reveals that the drug is preferentially targeting to liver followed by brain and lungs.

Age-related macular degeneration (AMD) is a leading cause of blindness in the modern world. The standard treatment regimen for neovascular AMD is the monthly/bimonthly intravitreal injection of anti-VEGF agents such as ranibizumab or aflibercept. However, these repeated invasive injections can lead to sight-threatening complications. Sustained delivery by encapsulation of the drug in carriers is a way to reduce the frequency of these injections. Liposomes are biocompatible, non-toxic vesicular nanocarriers, which can be used to encapsulate therapeutic agents to provide sustained release. The protein encapsulation was performed by a modified dehydration-rehydration (DRV) method. The liposomes formed were characterized for size, zeta potential, encapsulation efficiency, stability, in vitro release, and ex vivo release profiles. In addition, the localization of the liposomes themselves was studied ex vivo. Entrapment-efficiency of ranibizumab into 100-nm liposomes varied from 14.7 to 57.0%. Negatively-charged liposomes prepared from DPPC-DPPG were found to have the slowest release with a low initial burst release compared to the rest of liposomal formulations. The ex vivo protein release was found to slower than the in vitro protein release for all samples. In conclusion, the DPPC-DPPG liposomes significantly improved the encapsulation and release profile of ranibizumab.

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.

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