Nanoparticulate Transscleral Ocular Drug Delivery Jigar N Shah 1 , Hiral J Shah 2 , Anastasia Groshev 3 , Anjali A Hirani 3 , Yashwant V Pathak 3 and Vijaykumar B Sutariya 3* 1 Department of Pharmaceutics, Institute of Pharmacy, Nirma University, Gujarat, India 2 Department of Pharmaceutics, Arihant School of Pharmacy & BRI, Adalaj, Gujarat, India 3 Department of Pharmaceutical Sciences, USF College of Pharmacy, University of South Florida, Tampa, USA * Corresponding author: Vijaykumar B Sutariya, Department of Pharmaceutical Sciences, University of South Florida College of Pharmacy, 12901 Bruce B. Downs Blvd, MDC 30, Tampa, FL 33612, USA, Tel: (813) 974-5289; Fax: (813) 905-9890; E-mail: vsutariy@health.usf.edu Rec date: Mar 20, 2014; Acc date: Jun 2, 2014; Pub date: Jun 4, 2014 Copyright: © 2014 Sha et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Ocular drug delivery is one of the most challenging areas of drug delivery due to the unique mostly avascular nature of the major eye structures and presence of two blood barriers. Effectiveness of a more conventional systemic delivery falls short due to low drug levels in the eye tissue. Periocular approaches require penetration of fibrous sclera and present their own limitations. Utilization of nanotechnology presents new avenue of drug system development with potential to penetrate protective barriers and sustain ample tissue saturation. More specifically, transscleral delivery permits a range of applications in targeted delivery, gene, stem cell, protein and peptides, oligonucleotide, and ribozyme therapies. The exciting range of current applications is expounded in this review. Keywords: Ocular delivery; Transscleral delivery; Drug delivery systems; Nanotechnology; Nanoparticle; Drug delivery; Macular degeneration; Retina Introduction Ocular drug delivery has remained one of the most challenging tasks for pharmaceutical researchers. The unique and complex structure of the eye restricts the entry of drug molecules at the required site of action. The eye is anatomically divided into the anterior and posterior segments with the lens–iris barrier roughly demarcating the two segments. The anterior segment consists of the front one-third of the eye that mainly includes pupil, cornea, iris, ciliary body, aqueous humor, and lens while the posterior segment consists of the back two-thirds of the eye that includes vitreous humor, retina, choroid, macula, and optic nerve (Figure 1) [1,2]. Further, the anatomy of the eye presents a unique system with two barriers that prevents penetration of substances from the blood, namely, the blood- aqueous and blood-retinal barrier [3]. There are a large number of major diseases affecting the eye including Age-Related Macular Degeneration (AMD), Diabetic Macular Edema (DME), cataract, Proliferative Vitreoretinopathy (PVR), uveitis, Cytomegalovirus (CMV), and glaucoma. Table 1 highlights the classification, signs and symptoms and current treatment options for these diseases [4-38]. Ocular drug delivery methods to treat anterior segment disease include topical (i.e. eye drops, ointment), systemic, and periocular (i.e. subconjunctival injections, implants) administration routes. Figure 1: Schematic representation of major structure of the eye. The anterior segment includes pupil, cornea, iris, ciliary body, and aqueous humor. The lens separates anterior portion from posterior, which includes vitreous humor, retina, choroid, macular, and optic nerve. Sclera encasing the whole eye protects it impedes penetration of majority external agents. Reprinted with permission from reference [1] Disease Classification Signs and symptoms Treatment AMD Dry AMD (non-exudative) Break down of photoreceptors, retinal pigment epithelium (RPE) and choriocapillaries Specific high dose formulation containing antioxidants, zinc and vitamin supplements Shah JN et al., J Biomol Res Ther 2014, 3:3 DOI: 10.4172/2167-7956.1000116 Review Open Access J Biomol Res Ther ISSN:2167-7956 JBMRT, an open access journal Volume 3 • Issue 3 • 1000116 Journal of Biomolecular Research & Therapeutics J o u r n a l o f B i o m o l e c u l a r R e s e a r c h & T h e r a p e u t i c s ISSN: 2167-7956