clinical evaluation of novel methods for extending microneedle pore lifetime

181 Pages·2017·1.43 MB·English

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Theses and Dissertations--Pharmacy College of Pharmacy
2012
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Nicole K. Brogden
University of Kentucky, [email protected]
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Brogden, Nicole K., "CLINICAL EVALUATION OF NOVEL METHODS FOR EXTENDING MICRONEEDLE PORE
LIFETIME" (2012). Theses and Dissertations--Pharmacy. 8.
https://uknowledge.uky.edu/pharmacy_etds/8
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Nicole K. Brogden, Student
Dr. Audra L. Stinchcomb, Major Professor
Dr. Jim Pauly, Director of Graduate Studies
CLINICAL EVALUATION OF NOVEL METHODS FOR EXTENDING MICRONEEDLE
PORE LIFETIME

DISSERTATION

A dissertation submitted in partial fulfillment
of the requirements for the degree of Doctor of Philosophy in the
College of Pharmacy
at the University of Kentucky

By
Nicole K. Brogden
Lexington, Kentucky
Director: Dr. Audra L. Stinchcomb, Professor of Pharmaceutical Sciences
Lexington, Kentucky
2012
Copyright © Nicole K. Brogden 2012
ABSTRACT OF DISSERTATION

CLINICAL EVALUATION OF NOVEL METHODS FOR EXTENDING MICRONEEDLE
PORE LIFETIME

Microneedles are a minimally invasive method for delivering drugs through the
impermeable skin layers, and have been used to deliver a variety of compounds
including macromolecules, vaccines, and naltrexone. Microneedles can be applied to
the skin once, creating micropores that allow for drug delivery into the underlying
circulation from a drug formulation. The utility of this technique, however, is blunted by
rapid micropore closure. This research project sought to: 1) characterize micropore
lifetime and re-sealing kinetics, and 2) prolong micropore lifetime via inhibition of the
skin’s barrier restoration processes. Impedance spectroscopy was used as a surrogate
technique in animals and humans to measure micropore formation and lifetime. A proof
of concept study in humans, using impedance spectroscopy, demonstrated that
diclofenac (a topical anti-inflammatory) applied to microporated skin resulted in slower
re-sealing kinetics compared to placebo, in agreement with previous animal studies.
The clinical feasibility of prolonging micropore lifetime with diclofenac was confirmed via
7-day delivery of naltrexone through microneedle treated skin in humans (compared to
72 hour delivery with placebo). Lastly, naltrexone gels with calcium salts were applied to
microneedle treated skin (hairless guinea pigs) to restore the altered epidermal calcium
gradient; this method did not significantly extend micropore lifetime.

KEYWORDS: diclofenac, impedance, microneedles, naltrexone, transdermal

Nicole K. Brogden
Student’s signature
July 17, 2012
Date
CLINICAL EVALUATION OF NOVEL METHODS FOR EXTENDING MICRONEEDLE
PORE LIFETIME

By
Nicole K. Brogden

Dr. Audra L. Stinchcomb
Director of Dissertation
Dr. Jim Pauly
Director of Graduate Studies
July 17, 2012
Date
DEDICATION

This entire body of work is dedicated to my parents,
who have provided immense support, encouragement, and guidance throughout all of
my academic endeavors.
ACKNOWLEDGEMENTS

Listen to the MUSTN’TS, child,
Listen to the DON’TS,
Listen to the SHOULDN’TS
The IMPOSSIBLES, the WON’TS
Listen to the NEVER HAVES
Then listen close to me –
Anything can happen, child,
ANYTHING can be.
– Shel Silverstein

It is not an overstatement that this work could not have been completed without
the expertise and support of a large number of people. I extend my sincerest thanks to
Dr. Audra Stinchcomb for the opportunity to be involved in a clinically relevant and
human-focused research project. I have grown as both a pharmacist and research
investigator through completion of this work. Additionally, Dr. Stinchcomb was extremely
generous to support me in completing my studies at University of Kentucky after she
relocated for a new faculty position at University of Maryland, Baltimore. Next, I wish to
thank the complete dissertation committee, and outside examiner, respectively: Dr. E.
Penni Black, Dr. Charles Loftin, Dr. Susan S. Smyth, and Dr. Kimberly Anderson. My
committee was extremely supportive throughout my training, particularly after Dr.
Stinchcomb began her new position in Baltimore. Dr. Leslie Crofford, as my clinical
mentor and study physician on all of the human studies, has been generous beyond
words in the support she provided me. She selflessly agreed to mentor me through all of
my clinical work, and I am deeply grateful for her continued encouragement and
mentoring. The love and support of my parents, Kim and Katherine Brogden, has been
unwavering during my long academic training (from pharmacy school through residency
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and graduate school), and helped me maintain the continued drive to complete this
research project. Ken Clinkenbeard has provided consistent love, understanding, and
good coffee during my training, despite long hours and late nights. I would like to thank
all my labmates: Dr. Kalpana Paudel, Dr. Caroline Strasinger, Dr. Mikolaj Milewski, Dr.
Courtney Swadley, Priyanka Ghosh, Jessica Wehle and Dana Hammell - their help with
experiments and day to day lab activities was critical in finishing this project. Dr. Stan
Banks has been unbelievably helpful and supportive of my growth as a bench scientist
and his contributions to my training cannot be overstated. Several funding sources have
supported this work, including NIH and the Center for Clinical and Translational Science;
I appreciate their support and the help of everyone at OSPA for administering the grants.
The IRB and staff in the ORI have been extremely helpful as I’ve learned to
appropriately conduct human clinical studies. Thank you to the staff and veterinarians in
the animal facilities who assisted with animal studies and took excellent care of our
animals. All of the nurses and staff at the Center for Clinical and Translational Science
were extremely generous and patient as I learned the processes of clinical research, and
they were fantastic in their clinical skills. I would like to acknowledge Dr. Vladimir
Zarnitsyn and Dr. Mark Prausnitz (Georgia Institute of Technology) for their expertise
with the MN arrays and fabrication process, and for providing expert opinions on my
research efforts. Catina Rossoll, Tammi Young, Betsy Davis, Tammy Kamer, Barbara
Hurst, Rodney Armstrong, Janice Butner, and Lou Dunn have all helped me immensely
with administrative activities. I would like to extend a heartfelt thanks to my research
subjects, without whom this body of work would not have had much meaning. To all of
my friends who have provided study breaks, good laughs, and a sense of home for me
here in Kentucky – you’ll never understand how much that helped me towards achieving
my goals. Without all of these people, all from different facets of my life, this work would
have remained solely an idea, and would not have ever come to completion.
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TABLE OF CONTENTS

Acknowledgements ........................................................................................................... iii
List of tables ..................................................................................................................... xi
List of figures ................................................................................................................... xiii
List of abbreviations ........................................................................................................ xv
Chapter 1: Statement of the problem ................................................................................ 1
Chapter 2: Research hypotheses ...................................................................................... 4
Chapter 3: Research plan ................................................................................................. 7
3.1 Develop an impedance spectroscopy technique as a surrogate marker to
monitor micropore formation and lifetime .............................................................. 7
3.2 Characterize the kinetics of micropore closure following topical application of
diclofenac to microneedle-treated skin in healthy human volunteers .................... 8
3.3 Quantify in vitro diclofenac skin concentrations in Yucatan miniature pig
skin following one-time microneedle treatment and application of diclofenac ±
naltrexone .............................................................................................................. 8
3.4 Determine in vitro microneedle-enhanced transdermal flux of naltrexone
across Yucatan miniature pig skin in the presence of diclofenac ......................... 9
3.5 Establish the tolerability of a combination of a 3% diclofenac gel
and an 11% naltrexone gel on microneedle-treated skin in hairless guinea
pigs ........................................................................................................................ 9
3.6 Pharmacokinetic evaluation of microneedle/COX inhibitor-enhanced
transdermal 7-day delivery of naltrexone in healthy human volunteers .............. 10
3.7 Pharmacokinetic evaluation of microneedle-enhanced transdermal 7-day
delivery of naltrexone following restoration of the Ca2+ epidermal gradient in
hairless guinea pigs ............................................................................................. 11
Chapter 4: Background and literature review .................................................................. 12
4.1 Introduction .................................................................................................... 12
4.2 Structure and function of the skin .................................................................. 12
4.2.1 Stratum corneum ............................................................................ 13
4.2.2 Viable epidermis ............................................................................. 14
4.2.3 Dermis and microvasculature ......................................................... 15
4.3 Transdermal drug delivery ............................................................................. 16
4.3.1 Optimal properties of transdermally delivered drugs ...................... 17
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4.3.2 Routes of skin penetration .............................................................. 18
4.3.2.1 Intercellular ...................................................................... 18
4.3.2.2 Transcellular .................................................................... 18
4.3.2.3 Appendageal .................................................................... 18
4.3.3 Mathematical models of passive diffusion through the skin ............ 19
4.4 Enhancement methods in transdermal drug delivery .................................... 21
4.4.1 Chemical permeation enhancers .................................................... 21
4.4.2 Physical methods............................................................................ 22
4.4.2.1 Thermal ablation .............................................................. 22
4.4.2.2 Laser ablation .................................................................. 22
4.4.2.3 Jet injections .................................................................... 22
4.4.2.4 Dermabrasion .................................................................. 23
4.4.2.5 Sonophoresis ................................................................... 23
4.4.2.6 Iontophoresis ................................................................... 23
4.4.2.7 Electroporation ................................................................. 24
4.4.2.8 Microneedles .................................................................... 25
4.5 Tolerability and safety of microneedles ......................................................... 28
4.6 Micropore lifetime after microneedle treatment ............................................. 28
4.6.1 Effects of occlusion ......................................................................... 29
4.6.2 Geometry and physical properties of the microneedles .................. 30
4.6.3 Drug delivery window following microneedle treatment .................. 31
4.7 Extending micropore lifetime ......................................................................... 33
4.7.1 Processes involved in wound healing and barrier restoration ........ 33
4.7.1.1 Lipid synthesis pathway ................................................... 34
4.7.1.2 Catioinic ion gradients ...................................................... 35
4.7.1.3 Arachidonic acid pathway ................................................ 36
4.8 Naltrexone as an ideal model compound for exploring the kinetics of
micropore closure ................................................................................................ 38
4.8.1 Challenges with current naltrexone formulations ............................ 38
4.8.2 Physicochemical properties of naltrexone favoring microneedle-
enhanced delivery.................................................................................... 39
Chapter 5: Development of impedance spectroscopy techniques for measurement of
micropore formation ........................................................................................................ 40
5.1 Introduction .................................................................................................... 40
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