Human eye is prone to common viral infections and immune responses due to the external

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1 1. Human eye is prone to common viral infections and immune responses due to the external factors and auto immunological mediations. Viral infections such as Herpes Zoster and Herpes simplex Infections (herpetic keratitis), cytomegalovirus (CMV) infection in immunocompromised subjects and viral conjunctivitis which is a contagious infection and inflammation of the conjunctiva (Daniels et al., 2011). Considering the examples of immunological diseases of eyes, Posterior blepharitis, ocular rosacea, post-lasik dry eye, contact lens intolerance, atopic keratoconjunctivitis (Dry eye disease), graft-versus-host disease, and herpetic stromal keratitis are the common ocular disorders in the autoimmune mediated inflammatory manifestations occur (Rao., 2011; Durrani et al., 2011). For the management of viral infections, various anti-viral medications were prescribed [Enlisted in table 1] that commonly available in the form of systemic administrable dosage form. Table 1.1: Anti-viral drug therapy approved for ocular viral infections Drugs name Route of Administration Approved for Varicella zoster virus (VZV) and Herpes simplex virus (HSV) Acyclovir Intravenous, Oral or topical Brivudin Oral Famciclovir Oral Idoxuridine Intravenous Penciclovir Topical Trifuridine Eye drops Valaciclovir Oral Approved for Human Cytomegalovirus (HCMV) Nucleoside DNA polymerase inhibitors Ganciclovir Intravenous, Oral or Intra-vitereal Cidofovir Intravenous Valganciclovir Intravenous Although, some of them are present as topical ophthalmic dosage form but their dosing frequency is too high that commonly leads to the side effects and noncompliance to the DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 1

2 patients. Among the anti-viral medication, now a day s Ganciclovir (GCV) is commonly used by the ophthalmologist. Ganciclovir (GCV), an analog of 2 -deoxyguanosine plays an important role in the treatment of ocular viral infections. Currently, Conventional oral and topical medications are available for the GCV application. The recommended oral dose of GCV is 3.0 g/day that high dose results in dose-related toxicity including bone marrow suppression and neutropenia (Colin., 2007; McGavin et al., 2001). For the topical application, ophthalmic (eye) gel dosage form is available that recommended to be applied seven to eight time in a day till the condition is improved. Such frequent and repetitive application is totally non patient compliancable, rising nuisance and untoward effects (McGavin and Goa., 2001). Gel form also leads to the visual and accommodation disturbance in the initial of application. Moreover, it is also not a cost effective mean. To treat and manage the local ophthalmic viral disorders Topical ocular delivery of GCV in the form of liquid eye drop is valuable, Which is the most common route and desirable dosage form respectively when considering convenience of administration, the rapid local effect, accessibility of the ocular tissue, relative safety and clinical compliance of the patients. In case immune ocular manifestations, our perceptive of the pathophysiology of immune ocular disorders improves with upcoming research, new treatment approaches are being developed. Topical anti-inflammatory and immunomodulatory agents, such as Cyclosporin A (CYA), is now recommended now a day s particularly in the treatment of dry eye, as it is anticipated that they will correct the vicious cycle of inflammation and cell damage on the ocular surface (Utine et al., 2010). Continious and prolonged medication with Cyclosporin A (CYA) is associated with potential systemic side effect like renal dysfunction, tremor, hirsutism, hypertension, gum hyperplasia, cardiotoxicity (Utine et al., 2010; Donnenfeld et al., 2010). DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 2

3 Local administration is expected to avoid the various side effects associated with systemic delivery. However, the currently available systems using oils to deliver Cyclosporine A (CYA) topically are poorly tolerated and provide a low bioavailability (Pflugfelder., 2004, Lallemand et al., 2003). However, due to the high hydrophilic and lipophilic character of GCV and CYA respectively, unique physiological structures of eye and the rapid elimination, the conventional topical applications usually have quite limited therapeutic benefits due to the poor bioavailability over and into the ocular tissues. The poor bioavailability is due to a) quick dilution of the formulation after instillation by the tear film, b) exhausted into the nasolacrimal channel, c) limited capacity of cul-du-sac (30 μl), d) presence of compact barrier in the form of tear film, corneal and conjunctival epithelia that prevent the penetration and absorption into the intraocular region (Akhter et al, 2011). Development of nano- sized novel formulations is worthwhile in such cases of ophthalmic delivery as they are expected to prolong the pre-ocular retention and increase the ocular bioavailability. In recent year, Vesicular and lipidic nanoemulsion drug delivery systems such as liposome, nanoemulsion and niosomes were successfully studied in ophthalmic drug delivery to provide, control drug delivery, prolonged drug precorneal residence time and enhance ocular bioavailability. Drug enclosed in the vesicles and oily nano-droplets allows for an improved partitioning and transport through the cornea. Moreover, vesicles offer a promising avenue to fulfil the need for an ophthalmic drug delivery system that has the convenience of a drop, but will localize and maintain drug activity at its site of action (Kaur et al., 2000; Sahoo et al., 2008). However, the untailored formulated nano-lipidic systems are normally negative and neutral charged that may only improved the ocular bioavailability to some extent due to corneal permeation enhancement owing to their rapid clearance like conventional eye drops. Thus, an optimum delivery system should be the one which can be delivered in the form of eye drops, causing no blurred vision or irritability, and would need not more than one to two DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 3

4 administrations per day. It is expected that positively charged nano-carriers may enhanced the drug corneal retention, permeation and subsequently the ocular bioavailability than the neutral and negatively charged systems due the result of interaction of positively charged vesicles with the polyanionic corneal and conjunctival surfaces due to presence of mucin (Fresta et al., 1999; Tian et al., 2012). Figure 1 illustrated here showed the conceptualization of mucoadhesive nanocarriers s enhanced bio-available topical ocular drug delivery. Taking into the account of this theory, it was thought that the use of mucoadhesive cationic chitosan (CH) polymer is potentially worthfull for tailoring the niosomes to positively charge coated niosomes as using cationic lipid such as stearylamine as positive charge substance which may lead to irritation and potential toxic effect to the eye (Taniguchi et al., 1988; Tian et al., 2012). Figure 1: Illustration showing the conceptualization of mucoadhesive nanocarriers s enhanced bioavailable topical ocular drug delivery based on the polymer chain entangle and charge interaction between nanocarrier and the ve charged mucin layer over the corneal surface. It is reported from many studies about the negatively charged mucin and CH interaction induced enhanced concentration and residence time of the associated drug. CH has unique properties such as acceptable biocompatibility and biodegradability with low toxicity and high charge density, (Xu et al., 2003; Dornish et al., 1997). Moreover, CH exhibits DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 4

5 interesting physico-chemical characteristic with a good potential for ocular drug delivery such as bioadhesion (Illum, 1998; Paul & Sharma, 2000; Tian et al., 2012), prolonging the corneal residence time (De Campos et al., 2004; 2001; Felt et al., 1999) and penetrationenhancing properties, which were initially attributed to the modulation of the tight junction barrier between epithelial cells (Koch et al., 1998; Schipper et al., 1997). It was found that, CH increases cell permeability by affecting both paracellular and intracellular pathways of epithelial cells in a reversible manner without affecting cell viability or causing membrane wounds (Dodane et al., 1999; Artursson et al., 1994; Tian et al., 2012). Moreover, chitosan may impart favorable rheological behavior where, its solutions have shown pseudoplastic and viscoelastic properties. This behaviour is particularly important in ophthalmic formulations since it facilitates the retention while it permit the easy spreading of the formulation due to the blinking of the eye (Wang et al., 2011). Despite numerous scientific efforts, efficient ocular drug delivery remains a challenge for the pharmaceutical scientists. Consequently, the design of a system with improved drug delivery properties to the ocular surface would be a promising step towards the management of external ocular diseases. The main objective of the present work was to design and develop nano sized ocular drug delivery system particularly in form of in form of topically applicable eye drops expected to have better patient compliance by enhanced bioavailability and prolonged action due enhanced ocular retention. The specific objectives of the work were: To develop and validate UHPLC and UHPLC MSMS method for in vitro and in vivo analysis of model drug Ganciclovir and Cyclosporine A respectively. DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 5

6 To develop thermodynamically stable Chitosan- based muco-adhesive nanoemulsion (nanocapsules) for topical ocular delivery of Cyclosporine A and its in-vitro, in-vivo evaluation in rabbit as animal model. And development and in-vitro and in-vivo evaluation of CH- coated nano-sized niosomal Dispersion loaded with GCV and evaluation of the developed mucoadhesive nano-system for its controlled release and corneal permeation (in-vitro) and in-vivo performance evaluated in rabbit model for corneal retention, Ocular pharmacokinetic in rabbits. DESIGN AND DEVELOPMENT OF NANO SIZED OCULAR DRUG DELIVERY SYSTEM Jamia Hamdard 6