ENABLING SOLID LIPID NANOPARTICLE DRUG DELIVERY TECHNOLOGY BY INVESTIGATING IMPROVED PRODUCTION TECHNIQUES DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Michael D. Triplett II, B.S. * * * * * The Ohio State University 2004 Dissertation Committee: Approved By Professor James F. Rathman, Adviser Professor Jeffrey J. Chalmers Adviser Professor Kurt W. Koelling Graduate Program in Chemical Engineering ABSTRACT Industry estimates suggest that approximately 40% of lipophilic drug candidates fail due to solubility and formulation stability issues, prompting significant research activity in advanced lipophile delivery technologies. Solid lipid nanoparticle technology represents a promising new approach to lipophile drug delivery. Despite numerous research studies demonstrating improved therapeutic drug profiles, the commercialization of solid lipid nanoparticle technology remains limited. Physical instability and drug burst release have undermined performance while commercialization has been impeded by the lack of a large-scale, economically efficient production process. Research has been conducted with the objective of advancing solid lipid nanoparticle production technology. Formulation and process effects on solid lipid nanoparticle size distribution, stability, drug loading, and drug release have been investigated, culminating in a novel solid lipid nanoparticle synthesis approach based on electrohydrodynamic aerosolization. Utilizing a high-shear homogenization technique, effects of mixing speed, mixing time, and material concentrations were investigated using an experimental design approach. Experimentation showed stearic acid as the optimal lipid, sodium taurocholate as optimal cosurfactant, a 3:1 lecithin to sodium taurocholate ratio provided optimum performance, and mixing time and speed were inversely related to nanoparticle size and polydispersity. β-Carotene was successfully incorporated into stearic acid nanoparticles. β-Carotene entrapment efficiency was shown to have a maximum of 80 % with a mean of 40 %. Entrapment efficiency decreased with increasing β-carotene concentration. β-carotene was retained in the nanoparticles for one month, the maximum time period examined. A maximum β-carotene concentration of 0.39 mg/ml was obtained in the nanoparticle suspension. ii An electrohydrodynamic aerosolization device was designed and constructed for making solid lipid nanoparticles. Using water, sodium dodecyl sulfate, and potassium chloride, stable cone-jets were produced at voltages applied to the stainless steel needle ranging from -1.4 kV to - 6.2 kV. When commercial vegetable oil was substituted for water, stable cone-jets were produced at voltages from - 1.6 kV to - 5.7 kV. The use of electrohydrodynamic aerosolization to produce lipid nanoparticles was demonstrated. Using oleic acid, Pluronic F-68, and potassium chloride, particles possessing number distribution median diameters of 82 nm, 180 nm, and 210 nm were produced. Future electrohydrodynamic aerosolization device recommendations were included. iii Dedicated to Nanette for her unwavering support and encouragement, my parents for their nurturing and countless sacrifices on my behalf, and my family for whom I hope this accomplishment provides fulfillment and inspiration iv ACKNOWLEDGMENTS I thank my adviser, Jim Rathman, for his intellectual support, creativity, and objectivity that made this work possible, and for his stimulating discussions in the art and beyond. I am grateful to Jeff Chalmers for his unselfishness and informative insights. I thank Kurt Koelling for his many years of advice and camaraderie. I thank Hal Walker, Linda Weavers, Bob Brodkey, Jim Lee, and Dave Tomasko for sharing their research facilities and equipment. I thank Shona Patel, Mei Yee, Grady Marcum, Erica Jones, Gary Koenig, Brian Kellogg, and Patrick Bennett for their efforts as undergraduate researchers. This document would have been impossible without their tireless efforts and insights. I am privileged to have worked with so many talented people. I expect many great accomplishments in the years ahead from this group. On a special note, I thank Grady Marcum for his service to our great country, and I ask that God bless him during his imminent tour of duty in Iraq as part of the War on Terror. I thank the United States Department of Defense, specifically the Office of Naval Research, and the American Society for Engineering Education for the National Defense Science & Engineering Graduate Fellowship Program that supported my graduate studies. I hope that countless future Americans experience the privilege of receiving a National Defense Science & Engineering Graduate Fellowship. America’s national security and economic future depend on more Americans obtaining advanced science and engineering skills. v VITA February 23, 1975 …………………………. Born – East Liverpool, Ohio, USA 1997 ……………………………………….. B.S. Chemical Engineering, The Ohio State University. 1997 – 2000 ……………………………….. Engineer, Procter & Gamble Company, Cincinnati, Ohio, USA 2000 – 2001 University Fellow The Ohio State University 2001 – 2004 National Defense Science & Engineering Graduate Fellow, The Ohio State University FIELDS OF STUDY Major Field: Chemical Engineering vi TABLE OF CONTENTS Page Abstract…………………………………………………………………………………………... ii Dedication.……………………………………………………………………………………….. iv Acknowledgments……………………………………………………………………………….. v Vita………………………………………………………………………………………………. vi List of Tables..…………………………………………………………………………………… ix List of Figures.………………………………………………………………………………….... xi Chapters: 1. Introduction…………………………………………………………………………………. 1 2. Review of solid lipid nanoparticle technology……………………………………………… 11 2.1. Solid lipid nanoparticle overview……………………………………………………... 11 2.2. Lipid nanoparticle synthesis techniques………………………………………………. 13 2.3. Effect of lipids and surfactants………………………………………………………... 23 2.4. Solid lipid nanoparticle stability………………………………………………………. 24 2.5. Lipophile loading and release in lipid nanoparticles………………………………….. 33 2.6. Pharmacological performance of solid lipid nanoparticle systems…………………… 36 2.7. Conclusions……………………………………………………………………………. 37 3. Material and process effects on solid lipid nanoparticle synthesis…………………………. 44 3.1. Introduction……………………………………………………………………………. 44 3.2. Materials and methods………………………………………………………………… 48 3.2.1. Materials……………………………………………………………………… 48 3.2.2. Lipid nanoparticle preparation………………………………………………... 50 3.2.3. Particle size analysis………………………………………………………….. 51 3.3. Results and discussion………………………………………………………………… 52 3.3.1. Assessment of microemulsion synthesis approach…………………………… 52 3.3.2. Effects of lipid and surfactant chemistry……………………………………... 55 3.3.3. Response surface modeling of stearic acid nanoparticles…………………….. 69 3.3.4. Investigation into the effects of lipid mass fraction and cholesterol addition... 75 3.4. Conclusions……………………………………………………………………………. 76 4. Incorporation of β-carotene into stearic acid nanoparticles………………………………… 78 4.1. Introduction……………………………………………………………………………. 78 4.2. Materials and methods………………………………………………………………… 79 4.2.1. Materials……………………………………………………………………… 79 4.2.2. Lipid nanoparticle preparation………………………………………………... 79 4.2.3. Particle size analysis………………………………………………………….. 79 4.2.4. Crystalline phase determination……………………………………………… 80 4.2.5. Drug loading and release determination……………………………………… 80 4.2.6. Atomic force microscopy…………………………………………………….. 80 vii 4.3. Results and Discussion………………………………………………………………... 80 4.3.1. Assessment of β-carotene incorporation using a 5 component mixture design 80 4.3.2. Investigation of ethanol as a cosurfactant…………………………………….. 84 4.3.3. Loading and release of β-carotene from stearic acid nanoparticles…………... 88 4.3.4. Effect of β-carotene loading on lipid crystallinity……………………………. 96 4.3.5. Comparison of a nutraceutical product to β-carotene loaded stearic acid nanoparticles………………………………………………………………….. 100 4.4. Conclusions……………………………………………………………………………. 101 5. Electrohydrodynamic Aerosolization as a novel approach for the preparation of solid lipid nanoparticles………………………………………………………………………………… 103 5.1. Introduction……………………………………………………………………………. 103 5.2. Materials and methods………………………………………………………………… 109 5.2.1. Materials……………………………………………………………………… 109 5.2.2. Particle size analysis………………………………………………………….. 109 5.2.3. Image capture…………………………………………………………………. 109 5.3. Results and discussion………………………………………………………………… 109 5.3.1. Design and construction of EHDA system…………………………………… 109 5.3.2. EHDA system start-up and aerosolization of water solutions………………... 115 5.3.3. Aerosolization of vegetable oil solutions…………………………………….. 119 5.3.4. Aerosolization of oleic acid solutions and demonstration of nanoparticle formation……………………………………………………………………… 123 5.3.5. Ethanol attack on acrylic housing…………………………………………….. 125 5.3.6. Electrical potential modeling and implications for future designs…………… 126 5.3.7. Composite nanoparticle modeling and implications for future research……... 132 5.4. Conclusions……………………………………………………………………………. 138 5.5. Recommendations for future research………………………………………………… 139 Appendices: A. Sample photon correlation spectroscopy data file…..…………………………………. 141 B. Sample JMP journal file…..……………………………………………………………. 145 C. Matlab program used to model EHDA electrical potentials and fields……..…………. 151 D. Matlab program used to model drug release profiles………………………..…………. 154 E. Calibration