A Thesis entitled Development and Evaluation of a Nanomicellar Eye Drop Formulation of Dexamethasone for Posterior Uveitis by Soohi Patel Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Pharmaceutical Sciences Industrial Pharmacy _________________________________________ Sai Hanuman Sagar Boddu, Ph.D., Committee Chair _________________________________________ Jerry Nesamony, PhD, Committee Member _________________________________________ Kenneth S. Alexander, PhD, Committee Member _________________________________________ Patricia R. Komuniecki, PhD, Dean College of Graduate Studies The University of Toledo August 2014 Copyright 2014, Soohi Patel This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Development and Evaluation of a Nanomicellar Eye Drop Formulation of Dexamethasone for Posterior Uveitis by Soohi Patel Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Pharmaceutical Sciences Industrial Pharmacy The University of Toledo August 2014 The overall objective of this study was to develop a clinically acceptable, mixed nanomicellar eye drop formulation of dexamethasone (DEXSOLV) for treating posterior uveitis. Nanomicelles were formulated using polyoxyl 40 stearate (P40S) and polysorbate 80 (P80), which are approved by US FDA for ocular use. The nanomicellar formulation was characterized for critical micellar concentration, solubility of dexamethasone, pH, particle size, zeta potential, morphology, differential scanning calorimetry, in vitro drug release, clarity, stability, filtration efficiency, and sterility. Ocular tolerance and the tissue drug distribution of DEXSOLV were assessed in rabbits following single and repeated topical administration. Nanomicellar formulation of dexamethasone (0.1%) was successfully developed and characterized with an optimized composition of P40S/P80 = 7/3 by weight. Transmission electron microscopy images revealed the spherical structure of micelles. DEXSOLV was found to be stable at 4oC and 25oC for up to 6 months. No irritation or redness was observed in the treated eyes as compared to the untreated control iii rabbit eyes. Therapeutic concentrations of dexamethasone were observed in the rabbit retina and choroid following single and repeated topical administration. In conclusion, the nanomicelles of P40S and P80 could efficiently solubilize dexamethasone in their cores, resulting in a stable aqueous eye drop formulation. Using this eye drop formulation, dexamethasone concentrations could be maintained well above the minimum effective concentrations following topical administration. The proposed topical therapy would enhance patient compliance and minimize the side-effects associated with intraocular implants and intravitreal injections in posterior uveitis therapy. iv Dedicated to my beloved family Acknowledgements I would like to express my deepest gratitude to Dr. Boddu for providing me an opportunity to be a part of his research group. This work would not have been possible without his valuable advice and excellent support all throughout my research. He provided me with all the resources and guidance needed to succeed with this project. I would like to take this opportunity to thank Dr. Jerry Nesamony and Dr. Kenneth S. Alexander for being a part of my defense committee. I would also like to thank them for their insightful comments and encouragement throughout my undergraduate and graduate school. I would like to specially thank Dr. Caren Steinmiller for serving as a graduate faculty representative for my thesis defense. I would like to thank Dr. Himanshu Gupta for helping me with the in vivo studies. I would also like to thank Dr. Wayne Hoss for supporting me financially throughout my graduate school. I hugely extend my thanks to Chandrasekhar Garapati and Yangjie Wei for always helping me with my research and always being there, whenever I needed. I thank Khyati Patel for helping me with her artistic skills. I would like to thank Yatri, Ruchin, Khusbu, Hardik, Jay, Amrata, Drishti, Harish and Ruthwik for their cheerful support. Finally, I would like to thank my wonderful parents (Sonal and Maullin Patel), my sweet brother (Munjal Patel), my jovial nani, and my entire family, for their financial and emotional support, without whom this all would not have been possible. v Table of Contents Abstract .............................................................................................................................. iii Acknowledgements ..............................................................................................................v Table of Contents ............................................................................................................... vi List of Tables ................................................................................................................... viii List of Figures .................................................................................................................... ix 1. Introduction ....................................................................................................................1 1.1. Anatomy of the eye ...........................................................................................3 1.1.1. Conjunctiva ........................................................................................3 1.1.2. Cornea ................................................................................................5 1.1.3. Aqueous Humor .................................................................................7 1.1.4. Iris ....................................................................................................10 1.1.5. Lens ..................................................................................................11 1.1.6. Vitreous Humor ...............................................................................12 1.1.7. Sclera................................................................................................12 1.1.8. Retina ...............................................................................................13 1.1.9. Optic Nerve ......................................................................................14 1.2. Retinal Diseases ..............................................................................................15 1.2.1. Age-Related Macular Degeneration (AMD) ...................................15 1.2.2. Diabetic Retinopathy (DR) ..............................................................17 1.2.3. Diabetic Macular Edema (DME) .....................................................19 vi 1.2.4. Proliferative Vitreoretinopathy (PVR) .............................................20 1.2.5. Uveitis ..............................................................................................21 1.2.6. Cytomegalovirus Retinitis (CMV) ...................................................22 1.2.7. Glaucoma .........................................................................................23 1.3. Challenges to ocular drug delivery .................................................................24 1.4. Retinal drug delivery.......................................................................................26 1.5. Posterior penetration of topically instilled drugs ............................................29 2. Significance of Research..............................................................................................38 3. Development and Evaluation of a Nanomicellar Eye Drop Formulation of Dexamethasone for Posterior Uveitis ..........................................................................40 3.1. Abstract ...........................................................................................................40 3.2. Introduction .....................................................................................................42 3.3. Materials and Methods ....................................................................................45 3.4. Results and Discussion ...................................................................................55 3.5. Conclusion ......................................................................................................73 4. Preclinical Evaluation of a Nanomicellar Eye Drop Formulation of Dexamethasone for Posterior Uveitis Following Repeated Topical Administration .............................74 4.1. Abstract ...........................................................................................................74 4.2. Introduction .....................................................................................................75 4.3. Materials and Methods ....................................................................................77 4.4. Results and Discussion ...................................................................................79 4.5. Conclusion ......................................................................................................82 References ..........................................................................................................................83 vii List of Tables 3.1 Solubility study of dexamethasone with increasing surfactant concentration .......56 3.2 Clarity test of 0.1% dexamethasone mixed nanomicellar formulation ..................65