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Botulinum toxins in clinical aesthetic practice 2

  1. 1. Botulinum Toxins in Clinical Aesthetic Practice
  2. 2. SERIES IN COSMETIC AND LASER THERAPY Series Editors David J. Goldberg, Nicholas J. Lowe, and Gary P. Lask Published in association with the Journal of Cosmetic and Laser Therapy David J. Goldberg, Fillers in Cosmetic Dermatology, ISBN 9781841845098 Philippe Deprez, Textbook of Chemical Peels, ISBN 9781841842954 C. William Hanke, Gerhard Sattler, Boris Sommer, Textbook of Liposuction, ISBN 9781841845326 Paul J. Carniol, Neil S. Sadick, Clinical Procedures in Laser Skin Rejuvenation, ISBN 9780415414135 David J. Goldberg, Laser Hair Removal, Second Edition, ISBN 9780415414128 Benjamin Ascher, Marina Landau, Bernard Rossi, Injection Treatments in Cosmetic Surgery, ISBN 9780415386517 Avi Shai, Robert Baran, Howard I. Maibach, Handbook of Cosmetic Skin Care, Second Edition, ISBN 9780415467186 Jenny Kim, Gary Lask, Comprehensive Aesthetic Rejuvenation: A Regional Approach, ISBN 9780415458948 Neil Sadick, Paul Carniol, Deborshi Roy, Luitgard Wiest, Illustrated Manual of Injectable Fillers, ISBN 9780415476447 Paul Carniol, Gary Monheit, Aesthetic Rejuvenation Challenges and Solutions: A Global Perspective, ISBN 9780415475600 Neil Sadick, Diane Berson, Mary P. Lupo, Zoe Diana Draelos, Cosmeceutical Science in Clinical Practice, ISBN 9780415471145 Anthony Benedetto, Botulinum Toxins in Clinical Aesthetic Practice, Second Edition, ISBN 9780415476362 Robert Baran, Howard I. Maibach, Textbook of Cosmetic Dermatology, Fourth Edition, ISBN 9781841847009 David J. Goldberg, Alexander L. Berlin, Disorders of Fat and Cellulite, ISBN 9780415477000 Kenneth Beer, Mary P. Lupo, Vic A. Narurkar, Cosmetic Bootcamp Primer: Comprehensive Aesthetic Management, ISBN 9781841846989 Walter P. Unger, Ronald Shapiro, Robin Unger, Mark Unger, Hair Transplantation, Fifth Edition, ISBN: 9781616310066
  3. 3. Botulinum Toxins in Clinical Aesthetic Practice Second Edition Edited by Anthony V. Benedetto DO FACP Clinical Associate Professor of Dermatology Department of Dermatology University of Pennsylvania School of Medicine Philadelphia, Pennsylvania, USA and Dermatologic SurgiCenter Philadelphia, Pennsylvania, USA
  4. 4. First published in 2006 by Taylor & Francis This edition published in 2011 by Informa Healthcare, Telephone House, 69-77 Paul Street, London EC2A 4LQ, UK. Simultaneously published in the USA by Informa Healthcare, 52 Vanderbilt Avenue, 7th Floor, New York, NY 10017, USA. © 2011 Informa UK Ltd, except as otherwise indicated. No claim to original U.S. Government works. Reprinted material is quoted with permission. Although every effort has been made to ensure that all owners of copyright material have been acknowledged in this publication, we would be glad to acknowledge in subsequent reprints or editions any omissions brought to our attention. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, unless with the prior written permission of the publisher or in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P 0LP, UK, or the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA ( or telephone 978-750-8400). Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. This book contains information from reputable sources and although reasonable efforts have been made to publish accurate infor- mation, the publisher makes no warranties (either express or implied) as to the accuracy or fitness for a particular purpose of the information or advice contained herein. The publisher wishes to make it clear that any views or opinions expressed in this book by individual authors or contributors are their personal views and opinions and do not necessarily reflect the views/opinions of the publisher.Any information or guidance contained in this book is intended for use solely by medical professionals strictly as a supple- ment to the medical professional’s own judgement, knowledge of the patient’s medical history, relevant manufacturer’s instructions and the appropriate best practice guidelines. Because of the rapid advances in medical science, any information or advice on dosages, procedures, or diagnoses should be independently verified. This book does not indicate whether a particular treatment is appropriate or suitable for a particular individual. Ultimately it is the sole responsibility of the medical professional to make his or her own pro- fessional judgements, so as appropriately to advise and treat patients. Save for death or personal injury caused by the publisher’s negligence and to the fullest extent otherwise permitted by law, neither the publisher nor any person engaged or employed by the publisher shall be responsible or liable for any loss, injury or damage caused to any person or property arising in any way from the use of this book. A CIP record for this book is available from the British Library. ISBN-13: 978-0-415-47636-2 Orders may be sent to: Informa Healthcare, Sheepen Place, Colchester, Essex CO3 3LP, UK Telephone: +44 (0)20 7017 5540 Email: Website: For corporate sales please contact: For foreign rights please contact: For reprint permissions please contact: Typeset by Exeter Premedia Services Private Ltd., Chennai, India Printed and bound in the United Kingdom
  5. 5. Dedication This book is dedicated to those physicians who are committed to providing patients with the best medical care using state-of-the-art techniques; and to the coauthors who have contributed valuable time and expertise in the creation of this book. Lastly, to Dianne, whose encouragement and loving support permitted me to accomplish that which at times has appeared insurmountable.
  6. 6. vii Contents List of contributors viii Foreword ix Alastair Carruthers Preface x Anthony V. Benedetto Prologue The search for beauty: historical, cultural, and psychodynamic trends xi Caroline S. Koblenzer 1 Pharmacology, immunology, and current developments 1 K. Roger Aoki 2 Facial anatomy and the use of botulinum toxin 15 James M. Spencer 3 Cosmetic uses of Botulinum toxin A in the upper face 24 Anthony V. Benedetto 4 Cosmetic uses of Botulinum toxin A in the mid face 101 Anthony V. Benedetto 5 Cosmetic uses of Botulinum toxin A in the lower face, neck, and upper chest 140 Anthony V. Benedetto 6 Skin resurfacing with Microbotox and the treatment of keloids 190 Woffles T. L. Wu 7 Facial and lower limb contouring 206 Woffles T. L. Wu 8 Botulinum toxin type A treatment for Raynaud’s phenomenon and other novel dermatologic therapeutic applications 223 Irèn Kossintseva, Benjamin Barankin, and Kevin C. Smith 9 Botulinum toxins-A other than BOTOX® 234 Gary D. Monheit 10 Botulinum toxin B 240 Neil S. Sadick and Yekaterina Kupava 11 Botulinum toxin in the management of focal hyperhidrosis 248 Dee Anna Glaser 12 Medicolegal considerations of cosmetic treatment with botulinum toxin injections 263 David J. Goldberg Appendix 1 Muscles of facial expression 267 Appendix 2 The preparation, handling, storage, and mode of injection of onabotulinumtoxinA 272 Appendix 3 Patient treatment record 274 Appendix 4 Informed consent for the treatment of facial and body wrinkles with BoNTA 275 Appendix 5 Side-effects and contraindications to BoNTA injections 276 Index 279
  7. 7. viii List of contributors K. Roger Aoki PhD Vice President, Neurotoxins Research Program, Department of Biological Sciences, Allergan, Inc., Irvine, California, USA Anthony V. Benedetto DO FACP Clinical Associate Professor of Dermatology, Department of Dermatology, University of Pennsylvania School of Medicine, and Medical Director, Dermatologic SurgiCenter, Philadelphia, Pennsylvania, USA Benjamin Barankin MD FRCP Dermatologist, The Dermatology Centre, Toronto, Ontario, Canada Dee Anna Glaser MD Professor & Vice Chairman, Director Cosmetic & Laser Surgery, Department of Dermatology, Saint Louis University School of Medicine, Saint Louis, Missouri, USA David J. Goldberg MD JD Director, Skin Laser & Surgery Specialists of NY/NJ, New Jersey, Clinical Professor of Dermatology and Director of Laser Research, Mount Sinai School of Medicine, New York, and Adjunct Professor of Law, Fordham University School of Law, New York, New York, USA Caroline S. Koblenzer MD Clinical Professor of Dermatology, Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA Irèn Kossintseva MD University of British Columbia, Vancouver, British Columbia, Canada Yekaterina Kupava Sadick Research Group, New York, New York, USA Gary D. Monheit MD Monheit Dermatology Associates, South Birmingham, Total Skin & Beauty Dermatology Center, and Clinical Associate Professor, Department of Dermatology, Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, USA Neil S. Sadick MD Sadick Dermatology & Aesthetic Surgery, New York, New York, USA Kevin C. Smith MD FACP FRCPC (Dermatology) Dermatologist, Niagara Falls Dermatology and Skin Care Centre, Niagara Falls, Ontario, Canada James M. Spencer MD MS Clinical Professor of Dermatology, Department of Dermatology, Mount Sinai School of Medicine, New York, New York, and Medical Director, Spencer Dermatology & Skin Surgery Center, Saint Petersburg, Florida, USA Woffles T. L. Wu MD Woffles Wu Aesthetic Surgery & Laser Centre, Camden Medical Centre, Singapore
  8. 8. ix Foreword Dr. Benedetto is a well-known expert in both dermatology and aesthetic medicine. His especial area of expertise is the surgical or pro- cedural side of dermatology and he has spent many years perfecting skin cancer treatment techniques and treating many thousands of skin cancer patients successfully. However, he has also achieved a deserved reputation in the cosmetic world, especially in the use of botulinum toxin. For many years he has been interested in the application of botu- linum toxin, not just to the upper face but also to the lower face and especially in individuals with facial asymmetry. This elegant book is appropriate for all who are interested in this field of knowledge. It will be appreciated not only by health care workers who administer the toxin but also by those who enjoy its beneficial effects. The former will improve their skill in the use of the material and the latter will learn more about how botulinum toxin can be used for good. I encourage all of you who are interested in this topic to read this excellent book. Alastair Carruthers Vancouver, Canada September 2010 It is an honor and a pleasure to write a Foreword for the new edition of Dr. Benedetto’s book Botulinum Toxins in Clinical Aesthetic Practice. The first edition of this book, under the title Botulinum Toxin in Clini- cal Dermatology was very well received and much admired. However, time has moved on and it is time to update the information which was available in the earlier book. The amount of information about the botulinum neurotoxins and especially about their cosmetic use has increased dramatically in the last few years with new papers being pub- lished daily. It is important to have a synthesis of this new information and its integration into the previously available knowledge. In addi- tion, the range of individuals who are administering the toxin has increased significantly. Hence the new edition of this book. I have particularly appreciated Dr. Benedetto’s selection of his co- authors; each is an acknowledged expert in the area in which they are writing. Dr. Benedetto has written many of the “core” chapters himself but has called on the assistance of other experts in important topics such as cosmetic indications which are less used in North America. Readers will be delighted by the clear anatomic diagrams and apprecia- tive of the clear advice on the handling and dilution of the currently available toxins—subjects which have caused much confusion.
  9. 9. x Preface Just a few short years ago the compilation of different injection techniques for the cosmetic use of the then-available botulinum neurotoxins (BoNTs), namely BOTOX® Cosmetic and Myobloc™/ Neurobloc™, appeared to be a daunting undertaking. Because of the exponential developments in the clinical use of botulinum toxin A (BoNTA), this second edition quickly became a foregone conclusion. Maintaining the original mission of an instructional manual, this updated edition attempts to record the improvements that naturally have evolved from earlier injection techniques. It also introduces newer and innovative ways to utilize the different BoNTs that are presently available worldwide. In the United States, the glabella remains the only area of the face that is approved by the FDA for the cosmetic use of BOTOX® Cosmetic, now identified by its nonproprietary name of onabotulinumtoxinA. Consequently, except for the glabella, all the cosmetic injection tech- niques described in this edition, as in the previous one, apply to nonap- proved, off-label indications, which makes this book unlike most other textbooks in medicine. It is sobering to realize that throughout human existence men as well as women have always sought ways to improve their appearance. Dr. Caroline Koblenzer takes us through a historical interpretation of beauty and the beautiful and how the use of BoNT can supplement our patients’ incessant attempts to maintain the appearance of youthful- ness. Faced with an overwhelming amount of new scientific and tech- nical information, Dr. Roger Aoki updates us with some of the latest developments in the pharmacology and immunology of BoNTs. Understanding functional anatomy cannot be over emphasized and Dr. James Spencer has made a concerted effort to apply his knowledge of anatomy in a meaningful and practical way as it relates to the use of BoNTs. The nuclear chapters on treating the face, neck, and chest with injections of BoNTA have been reorganized and expanded, assimilat- ing a number of improved injection techniques with the plethora of recently published clinical articles. Dr. Woffles Wu, one of the early initiators of the intradermal use of BoNTA, has complemented this edition with his innovative techniques of muscle contouring and skin redraping. Reducing muscle bulk and girth of various parts of the body are techniques that are frequently practiced in the East and are quickly becoming popular in the West. Dr. Kevin Smith continues to impress us with avant-garde uses of BoNTA for treating Raynaud’s phenomenon and other painful conditions and scars as well as describing potential techniques for lifting the female breasts with injections of BoNTA. He also presents some tips on the management of an acute overdose of BoNTA. OnabotulinumtoxinA (BOTOX® Cosmetic) is no longer the only BoNTA approved in the United States. As anticipated in the first edi- tion, DYSPORTTM (abobotulinumtoxinA) finally made its debut in the U.S. market about a year ago. Dr. Gary Monheit, who headed the U.S. clinical trials for onabotulinumtoxinA, has updated the injection tech- niques for its clinical use. He also previews the pharmacology of the noncomplexed (naked) BoNTAs and introduces incobotulinumtox- inA, a “naked” BoNTA currently used in Europe, Mexico, and South America and soon to be introduced into the U.S. market. He also gives us a peek into the future with as much information currently permis- sible about a topical BoNTA presently undergoing phase II and III clinical investigation. The chapter on BoNTB (rimabotulinumtoxinB), the only nontype A neurotoxin approved by the FDA, has been updated by Dr. Neil Sadick. Dr. Dee Anna Glaser, current President and Found- ing Member of the International Hyperhidrosis Society, has revised and updated the chapter on hyperhidrosis. Another enhancement to this edition is Dr. David Goldberg’s expert rendition of medicolegal considerations for those physicians who treat patients for cosmetic purposes. This important aspect of medical prac- tice rarely is addressed, but there are pertinent issues of which we should be aware. Particular recognition and a special expression of gratitude is due to Lisa Van Horn for her organizational skills and secretarial expertise that facilitated the completion of this book. Finally, we are all indebted to those physicians who have treated and continue to care for patients with BoNTs for therapeutic and cosmetic purposes. Their commitment to the improvement of their patients through the advancement of sound and effective medical care should be lauded and emulated. Anthony V. Benedetto DO FACP September 2010
  10. 10. xi prologue The search for beauty: historical, cultural, and psychodynamic trends Caroline S. Koblenzer INTRODUCTION Why, one may ask, in a social climate where poverty is rife and the delivery of basic health care, if not absent, certainly unevenly distri- buted, why is the search for what is perceived as physical beauty still so much a part of the lives of so many? This question has generated con- siderable sociologic research (1–4), and that it is indeed the case, is demonstrated by the nearly $12 billion that was spent on cosmetic pro- cedures in 2008 alone (5). In order for us to appreciate the reasons for this vast expenditure, it is important for us to understand that inher- ently there is, at any given time, a “consensual view,” a stereotype, of what constitutes beauty (1–4), and how, if one is to be successful in life, it is important that one do one’s best to conform to that stereotype for a number of very important and indeed realistic reasons. In what follows, we will consider the ways in which the consensual view of beauty in Western civilizations, and most particularly in North America, has changed over the centuries. This in contrast to the Orient where traditional esthetics remained firmly in place until Western influences were introduced. How the view has changed for both men and women, and some of the forces that have led to those changes will also be considered, while in order to understand better the ongoing need to try to conform to the prevailing stereotype, the psychological development of the body image, and how the way one feels about one- self and about that image impact one’s performance in every sphere of life, will also be described. Finally, aspects of the current stereotype and what forces are at work to determine its form will be discussed, as will the impact on the psychosocial well-being of the individual, when attempts are made to achieve the stereotype. THE CONSENSUAL VIEW OF BEAUTY As noted, there is generally held to be a consensual agreement within a given culture as to what features are deemed beautiful, though clearly there is great variability between cultures as to what particular charac- teristics are desired (4). One certainly might wonder how such a con- sensual decision could be arrived at, and indeed studies are under way to determine which parts of the brain are activated, and what affective stimuli are involved, when the level of beauty of a given face is under consideration (6,7). Western literature is replete with discussion as to whether or not physical beauty equates to moral goodness and whether it necessarily parallels physical health (1,8). To some, it is merely a“new indicator of social worth” (8), and, indeed, historically it appears that there has been a “trickle-down” effect, as concepts of beauty espoused by the rich have passed down through the socioeconomic levels to become more widely held (9). An anthropologic view is that we are—unconsciously, one would presume—intent only on procreation and thus we find attractive those features that would point to procreation as a possibility (3,6,10–12). These features have been characterized as symmetry of face and body, full lips, smooth clear skin, clear eyes, lustrous hair, good muscle tone, animated facial expression, and a high energy level—features that one would intuitively associate with good health, certainly, although studies suggest that these features are not necessarily associated with fertility (10–14). But one need only look at art through the ages to see that this par- ticular stereotype has not always been sought, and that the consensual view of beauty has changed back and forth over time, as has been well-summarized in the literature (3,10,14). In the Middle Ages, for example, Western feminine beauty was portrayed as fragile and ethereal—a reflection, perhaps, of the veneration of women that was characterized in tales of chivalry—while later, in the sixteenth and sev- enteenth centuries, beautiful women were portrayed as much more robust. By the eighteenth century, fragility had returned, and in the early part of the nineteenth century, the frail, pale willowy woman was once again regarded as the beauty ideal, an ideal that it is suggested was consonant with the puritanical prudishness of the time. Later, in the latter part of the century, a much more robust, heavier-set woman emerged as a beauty, reflecting the fact that times had become eco- nomically easier, and the middle classes were more financially secure. This more heavy-set, robust style of femininity was in turn superseded by a muscular, athletic-looking woman, as sports began to be intro- duced on college campuses, and women started to take a more active part in the working world (3,10). Just as in women, the consensual view of beauty in men has also changed over the years. In the mid-1800s the male ideal was pale and thin, “dyspeptic men, the puny forms, and the bloodless cheeks” due perhaps to lack of exercise and the “prevailing air of serious business.” It was stated at the time that “a straight back and a well-carried chest” meant that a man was either a “soldier or a foreigner” (15). Lord Byron’s look was that most admired, with “chiseled features, great fine- ness and silkiness of the hair, and tapering extremities,” and indeed, Byron reputedly was wont to subject himself to diet regimens to main- tain that look, perhaps an early—and indeed male—example of body dysmorphic issues and anorexia, problems that, particularly in young women, are very much with us today. Prince Albert, the Prince Con- sort, was slender and with fine features, and of course Napoleon, another admired character, was short (16). In the latter part of the nineteenth century, this somewhat esthetic concept of beauty was reversed completely as European immigrants to America brought with them traditions of physical exercise and dedica- tion to outdoor sports.Andrew Jackson, the frontiersman, assumed the presidency, and the “trickle-down effect” on taste was clear, as men, eager to display their financial prosperity, showed off their rubicund faces and protruberant abdomens (19). By the early 1900s, this again had changed, and the new image of youthful masculinity and beauty was a tall and athletic figure, with fine features (16–18). Though cosmetics had been associated initially with royalty and the aristocracy, and later with prostitution and the theater, even two hun- dred years ago many ordinary women lightened their complexions by ingesting or applying arsenic in addition to guarding their skin from sunlight. By then cosmetic manufacturers were advertising more exten- sively, and the more widespread use of their products was justified by such terms as “elegant,”“stunning,” and “chic” (19). THE CURRENT CONSENSUAL VIEW More than any prior generation, our current consensual beauty ideal of both face and body, male and female, is generated to a large extent by our exposure to omnipresent advertising by the cosmetic, fashion and media industries, and most recently by some of our colleagues. This advertising may be in print, on-line, or on the air, but it constantly
  11. 11. xii BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE reminds us that we may be falling short, in one way or another (8,20–27). Today’s ideal for women is young, very slender and clad in the fashions sported by the models and media idols whom we see, whether or not we choose, several times each day. Her complexion is smooth and beautifully enhanced by the clever application of cosmet- ics (28), her hair glistening, and her muscles toned. Yet, interestingly in one study, when questioned, young women found those faces that most approximated the mean, rather than the ideal, to be the most attractive (22). For men, though still young and slim, the ideal handsome male has defined clean-cut masculine features, and most importantly, slen- der bodies with well-defined muscles (1). In both sexes, as the indi- vidual progresses through the different phases of life, from childhood to old age, these concepts of beauty and how that person perceives himself or herself in relation to the prevailing concepts remain crucial, and the goal for the emotionally healthy is still to strive to meet them. In both, symmetry is important and in both, youth is of the essence (1,3,12,28–30). In either case, as Hilhorst notes, beauty can be achieved by “cultural means” and thus it expresses both our present culture, and our per- sonal choices (2,3). These choices, in turn, are determined by the way in which we perceive ourselves, how we feel about that perception, and how we compare it with others. In other words, despite the fact that our choices are strongly influenced by the prevailing ideal, choices about the way we display ourselves are made fundamentally on the basis of our body-image and our self-esteem—two aspects of the self that are integral to the personality at every phase of life (2,31–35). Body Image and Self-esteem What we understand by “body-image” is complex and multidimen- sional. It is not only “the picture of our own body that we form in our own mind” (32), but also the way that we feel about ourselves. Having both physical and psychologic components, body-image is intimately associated with self-esteem. Clearly this complex is of some impor- tance, since the way in which we see ourselves, whether it pleases us or whether we see deficiencies, affects every aspect of our lives—our thoughts, our emotions, and our relationships (31). Development of Body Image and Self-esteem One may wonder why it is that for one person even a minor flaw in appearance is devastating, while for another that flaw, or even greater disfigurements, may be of no consequence whatsoever. Infant observa- tion studies have shown that these very different feelings about oneself have their beginnings during one’s very early life experience, and evolve in the context of one’s earliest relationships (35). The emotional environment for the infant is contained within the relationship between the infant and the primary caretaker. In the recip- rocal interaction that takes place between the two, if tactile stimulation is congruent with the infant’s needs, and the environment accepting, the infant will begin to incorporate and make a part of himself or her- self both a capacity to modulate anxiety, and an understanding of the boundaries between the self and the other, with an appreciation of his or her own size, shape, and physical configuration. The quality and the amount of empathic touching that takes place within this fundamental relationship will help to determine the integrity of the body image, how close it is to reality, and whether the feelings about the self that are generated, are positive or negative. When the caretaker is in tune with the infant’s feelings, expressing love and admiration in smile and touch, the body-image will be stable, the boundaries firm, the self-esteem positive, and the individual confident and secure (33,34). The inner feelings aroused in this early stage of development are reinforced by parental attitudes as the child grows. Parental values and expectations with regard to looks and behaviors—what is perceived as beautiful or good—are transmitted verbally and nonverbally to the child, and whether these parental attitudes are overtly met with cooperation or with opposition, at some level most children wish to grow up to be like the parents, and to please them and make them proud. However, the reverse is also true—when demanding, perfectionistic, and rigid par- ents have expectations that are unrealistic, the inevitable parental dis- appointment or dissatisfaction is, in like fashion, internalized by the child, becoming a part of the self, and impacting the body-image and the quality of self-esteem (34). Feelings of guilt arise, and dissatisfac- tion with different aspects of the self may later lead to anxiety or depression, and to disquieting issues about lack of goodness or beauty, with feelings of ugliness associated with a poor personal presentation. Progressing into adolescence, the child must separate emotionally from the parents in order to develop an individual identity. Aspects of the parents that the child admires will be incorporated and integrated into the personality, but as the child separates, it is peers, father-figures or sports idols who become the ones to emulate in looks, dress, and the ideals of masculinity for boys. Indeed the boy may try out many styles, perhaps carried to extremes—for example body piercing, tattoos, etc.—before arriving at his own comfortable identity. For the girl the task is more difficult, as she is still under great pressure to please the mother and to incorporate admired maternal traits. She too must struggle to separate, and at the same time emulate in attitude and style, the peers, models and media idols that she so admires. For both boys and girls acceptance by the peer group, and the“sameness”as peers, are of paramount importance for emotional well-being (31,32). As the adolescent matures, the body-image and self-esteem become established as psychological entities, and come to settle at some point along the broad spectrum of affects, from positive to negative. In adult life, social interaction and appearance-related feedback serve to rein- force, or exaggerate the individual’s feelings about the internalized per- sona, whether those feelings be positive or negative (37). It is important to note that the powerful impact of the media on those feelings, cannot be overestimated (3,20–25). WHY AIM TO EMULATE THE IDEAL? And so what are the advantages of emulating the current cultural ideal of beauty, in so far as one is able? Those who most closely approximate the ideal, although they may serve as objects of comparison for the less well-favored, generating envy, nevertheless have enormous personal, social, and professional advantages, as many studies have shown. A small sampling will serve to illustrate this point. In terms of subjective experience, physically attractive people report- edly receive more social reinforcement, have closer relationships, and experience greater intimacy and greater satisfaction in their sexual interactions than do those less favored (38,39). Objectively, examples of the benefits of conforming to the current consensual ideal of beauty can be found in essentially every aspect of life. Pretty children, for example, get better grades than those perceived as plain; plain children attract greater antipathy from their fathers (40); pretty waitresses get better tips (41); physically attractive men and women are more readily hired, receive earlier promotions, and make more money than do those who less clearly approximate the current consensual ideal (2,42); while women tend to marry those of equivalent good looks, so that the beau- tiful woman is more likely to get the handsome husband (43). It may also be that those who are physically and attractively well-endowed bring out good qualities in others; for example in one study, when a man believed himself to be speaking to a beautiful woman by tele- phone, he was found to make conversation that was significantly more interesting than in the obverse (44). It is important for us to remember that the media images that we cannot avoid, and that reflect our current consensus of what is beauti- ful, are not wholly realistic, as they have been touched-up, air-brushed, and enhanced in a number of ways (42). But it is plain that ours is a
  12. 12. xiiiPROLOGUE: THE SEARCH FOR BEAUTY: HISTORICAL, CULTURAL, AND PSYCHODYNAMIC TRENDS culture of youth, and as the population ages, and as economic condi- tions deteriorate, men and women are tending to work longer, and to retire at a greater age, thus increasing competition in the workplace. In order to remain competitive, men like women are struggling to look younger, healthier, more physically active, and more consonant with the current ideal of masculine good looks. Thus both men and women are seeking cosmetic improvement in greater numbers than ever before (3,5,8,21,26,42,45–47). Clearly we are not dealing in absolutes, and as noted earlier, there is a broad spectrum that encompasses the different levels of emotional health that we encounter in practice (31,35,46–48) At one end of the spectrum is the successful individual who has a generally positive self- esteem, but who may have physical features that for one reason or another, he/she may want to change a little, or make more youthful. Such an individual will have goals that are realistic, and is likely to be satisfied by the results of any procedure that is undertaken. The narcissistic individual may have an entirely realistic view of his or her appearance, but yet may find it imperfect for one or another reason, and seeking perfection, may demand procedures that will not satisfy, because, of course, that individual’s view of perfection may not be attainable (49). At the other end of the spectrum is the unfortunate person for whom early life experience has led to a negative and insecure body-image with boundaries that are not firm, poor self-esteem, and a depressive affect (33,34). This person makes constant negative comparison with others, both anticipating and attracting negative social feedback in a way that generates a destructive emotional downward spiral. For this person, social situations become progressively more uncomfortable, intimacy is to be avoided, and survival in the workplace may be threatened. Such a person, in defense against these depressive feelings of hopelessness, may deride those who seek ways to improve themselves. Alternatively, such a person may seek ever more radical interventions—surgical or nonsurgical—to improve the real or less-real perceived deficits in face or body configuration that have come to dominate that person’s life (48). Body dysmorphic disorder is the name given to the condition in which there is no abnormality, or a very minor abnormality, that is perceived by the individual in a negative way, which is out of propor- tion to the reality. The perception of abnormality may be relatively mild or of frankly delusional proportions and may lead the individual to engage in behaviors that are self-destructive (42,47,48). These are the patients who may have anorexia or bulimia, or who may demand ever more radical surgical interventions from the cosmetic surgeon. It is of critical importance to recognize this syndrome, since nothing that the surgeon undertakes will satisfy, and both suicide of the patient and murder of the surgeon are reported (49–51). And so, though beauty may indeed be “in the eye of the beholder” (52), should that beholder be the self, looking into the mirror, the search for beauty may become a very important part of that behold- er’s life, in ways that will depend on the psychological make-up of that same beholder. Clearly, in some this may be healthier than in others. In the earlier histories of man, age and the acquired wisdom of the years was respected. Aging Greek philosophers such as Plato and Aristotle, though not young, were valued for their wisdom—indeed there was once the concept that age was beautiful (53). Sadly, during our current generation this view does not hold sway.Youth, and all that youth implies,is the most valuable attribute,and the search for youth— at least as far as looks are concerned—seems to be insatiable. Hence, the rush for botulinum toxin. Botulinum toxin injections, by eliminating wrinkles, can not only temporarily erase the ravages of time, and create a younger look, but they may also be employed to generate symmetry of face and body (54). Thus, although there are increasing numbers of medical conditions for which botulinum toxin has been found effective (55–58), if we look back anthropologically, by engendering this symmetry, together with a smooth, clear skin, botulinum toxin can help to create the physical features historically believed to signify fertility—perhaps another of the unconscious motivators in the current botulinum toxin craze (3,6,10–12). The “trickle-down” wish by the less socially privileged to enjoy the same physical features that characterize those of greater privilege (9) may play a part here also. In our media-driven age, the “privileged”— those of the “rich and famous” media idols, sports figures, and models that we see in so many venues each day—are either very young, or, by dint of hard work, and often at considerable expense, have erased wrin- kles, unwanted body weight, and others of the possible signs of aging. Thus it is often the goal of those of us of perhaps lesser “privilege” to emulate that same look in so far as we can, providing yet another force that contributes to the botulinum toxin craze. Finally, as noted, while medical advances are prolonging healthy life, economic forces are making it necessary for many to work past the usual retirement age. As younger people enter the workforce, their energy and youthful good looks are both psychologically and realisti- cally threatening to those of more advanced age. And so it is clear that, at this time at least, there are not only deeply entrenched psychological reasons for us to do our best to conform to the current cultural ideal of beauty. Given the realities of our world, and given that our current cultural ideal is one of youth, there are also many very realistic reasons for us to try to emulate that ideal. One way that we can do so—a way that is currently popular for reasons that this book will explain—is by jumping onto the botulinum toxin bandwagon. REFERENCES 1. Leist A. What makes bodies beautiful. J Med Philos 2003; 28(2): 187–219. 2. Hilhorst MT. Physical beauty: only skin deep? Med Health Care Philos 2002; 5: 11–21. 3. Sarwer DB, Grossbart TA, Didie ER. Beauty and society. Semin Cutan Med Surg 2003; 22(2); 79–92. 4. Jackson L. Physical attractiveness. A sociocultural perspective. In: Pruzinski T, Cash TF, eds. Body Images. New York: The Guilford Press, 2002: 13–21. 5. American Society for Aesthetic Plastic Surgery. Cosmetic Surgery National Data Bank Statistics 2008. Available at sites/default/files/2008stats.pdf (accessed November 4, 2010). 6. Nadal M, Munar E, Capo MA, Rossello J, Cela-Conde CJ. Towards a framework for the study of the neural correlates of aesthetic pref- erence. Spat Vis 2008; 21(3–5): 379–96. 7. Santos IM, Young AW. The effects on inversion and negation on societal inferences from faces. Perception 2008; 37(7): 1001–78. 8. Honigman R, Castle DJ. Aging and cosmetic enhancement. Clin Intervent Aging 2006; 1(2): 115–9. 9. Banner LW.American Beauty.NewYork:AlfredW.Knopf,1983: 3–8. 10. Pawlowski B, Boothroyd LG, Perrett DI, Kluska S. Is female attrac- tiveness related to final reproductive success? Coll Antropol 2008; 32(2): 457–60. 11. Swami V, Furnham A. Joshi K. The influence of skin tone, hair length, and hair color on ratings of women’s physical attractive- ness, health and fertility. Scand J Psychol 2008; 49(5): 429–37. 12. Rhodes G. The evolutionary psychology of facial beauty.Annu Rev Psychol 2006; 57: 199–226. 13. Fink B, Neave N. The biology of facial beauty. Int J Cosmet Sci 2005; 27(6): 317–25. 14. Banner LW. American Beauty. New York: Alfred Knopf, 1983: 45–65.
  13. 13. xiv BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE 15. Parker-Willis N. Rag-Bag: A Collection of Ephemera. New York: Charles Scribner, 1855: 22. 16. Stuart- Wortley E. Travels in the United States in 1849–1850,Vol 1. New York: Harper Bros, 1851: 54–5. 17. Sala GA. America Revisited. London: . Vizzatelli, 1882: 65. 18. Beard G. Physical future of the American people.Atlantic Monthly. 1879; 43: 7325. 19. Brenner LW. American Beauty. New York:. Alfred Knopf, 1983: 28–44. 20. Yamamiya Y, Cash TF, Melnyk SE, Posavac HD, Posavac SS. Wom- en’s exposure to thin-and-beautiful media images: Body-image effect on media-ideal internalization and impact-reduction inter- ventions. Body-Image 2004; 2(1): 74–8. 21. Crocket, RJ, Pruzinsky T, Persing JA. The Influence of plastic sur- gery “reality-TV” on cosmetic surgery patient-expectations and decision-making. Plasst Reconstr Surg 2007; 120(1): 316–24. 22. Aherne AL, Bennett KM, Hetherington MM. Internalization of the ultra-thin ideal: Positive associations with underweight fashion models are associated with drive for thinness in young women. Eat Disord 2008; 16(4): 294–307. 23. Hargreaves D. Tiggemann M. The effect of television commercials on mood and body dissatisfaction. The role of appearance schema activation. J Soc Clin Psychol 2002; 21: 328–49. 24. Potter T, Corneille O. Locating attractiveness in the face space: Faces are more attractive when closer to their group prototype. Psychon Bull Rev 2008; 15(3): 615–22. 25. Tiggemann M. Media influence on body image development. In: Cash TF, Pruzinky T, eds. Body Image: A Handbook of Theory, Research and Clinical Practice. New York: The Guilford Press, 2002: 91–8. 26. Schlessinger J. Skin care for men and its marketing. Dermatol Ther 2007; 20(6): 452–6. 27. Hermann B. Ideals of beauty and the medical manipulation of the body between the free choice and coercion. Ethic Med 2006; 18(1): 71–80. 28. Mulherne R, Fieldman G, Hussey T, Leveque JL, Pineau P. Do cos- metics enhance female Caucasian facial attractiveness? Int J Cos- met Sci 2003; 25(4): 199–205. 29. Koblenzer CS, The psychologic effects of aging and the skin. Clin Dermatol 1996; 14: 171–7. 30. Grosslink CK, Cox CL, McClure SJ, DeJong ML. Ravishing or rav- aged: Women’s relationships with women in the context of western beauty culture. Int J Aging Hum Dev 2008; 66(4): 307–27. 31. Kreuger DW. Psychodynamic perspectives on body image. In: Cash TF, Puzinski T, eds. Body Image. New York: The Guilford Press, 2002: 30–46. 32. Kreuger DW. Developmental and psychodynamic perspectives in body image. In:Cash TF, Pruzinski T, eds. Body Images. New York: The Guilford Press, 1990: 255–71. 33. Weiss SJ. Parental touching: Correlates of a child’s body concept. In: Barnard KE, Brazelton TB, eds. Touch, the Foundation of Experi- ence. Madison, CT: International Universities Press, 1990: 425–50. 34. McDevitt JB, Mahler MS. Object constancy, individuality and internalization. In: Greenspan SI, Pollock GH, eds. The Course of Life, Vol. 11: Early Childhood. Madison CT: International Univer- sities Press, 1989: 37–57. 35. Beiser HR. Ages 11–14. In: Greenspan SI, Pollcock GH. eds. The Course of Life, Vol 1V: Adolescence. Madison, CT: International Universities Press, 1991: 106–15. 36. Staples HD, Smarr ER. The Bridge to adulthood. In: Greenspan SI, Pollcock GH. eds. The Course of Life, Vol 1V: Adolescence, 1991: 407–25. 37. Cash TF, Fleming EC. Body image and social relationships. In: Cash TF, Pruzinsky T, eds. Body Image. New York: The Guilford Press, 2002: 277–86. 38. Cash TF. The psychology of physical appearance. In: Cash TF, Pru- zinski T, eds. Body Images. New York: International Universities Press, 1990: 51–7. 39. Koblenzer CS. Psychosocial aspects of beauty: How and why to look good. Clin Dermatol 2003; 21: 473–5. 40. Elder GH Jr, Nguyen TG, Caspi A. Linking family hardship to chil- dren’s lives. Child Devel 1985; 56: 361–75. 41. Lynn M. Determination and consequences of female attractiveness and sexiness: Realistic tests with restaurant waitresses. Arch Sex Behav 2009; 38(5): 737–45. 42. Grossbart TA, Sarwer DB. Cosmetic surgery: surgical tools— Psychosocial goals. Semin Cutan Med Surg. 1999; 18(2): 101–11. 43. Lee L, Loewenstein G, Hong J, Young J. If I’m not hot, are you hot or not? Physical attractiveness evaluations and dating preferences as a function of one’s own attractiveness. Psychol Sci 2008; 19(7): 669–77. 44. Wack ER, Tantieff-Dunn S. Cyber sexy: Electronic game-play and perceptions of attractiveness among college-aged men. Body Image 2008; 5(4): 365–74. 45. The American Society for Aesthetic Plastic Surgery. Cosmetic Sur- gery Quick Facts: 2005 ASAPS Statistics. press/procedurefacts. 46. Grossbart TA, Sarwer DB. Psychosocial issues and their relevance to the cosmetic surgery patient. Semin Cutan Med Surg 2003; 22(2): 136–47. 47. Castle DJ, Honigman RJ, Phillips KA. Does cosmetic surgery improve psychosocial wellbeing? Med J Austral 2002; 176(12): 601–4. 48. Malick F, Howard J, Koo J. Understanding the psychology of cos- metic patients. Dermatol Ther 2008; 21(2): 151. 49. Castle DJ, Phillps KA, Dufresne RG Jr. Body dysmorphic disorder and cosmetic dermatology: more than skin deep. J Cosmet Derma- tol 2004; 3(2): 99–103. 50. Ritvo EC, Melnick I Marcus GR, Glick ID. Psychiatric conditions in cosmetic surgery patients. Facial Plastic Surg 2006; 22: 194–7. 51. Cotterill JA, Cunliffe WJ. Suicide in dermatology patients. Br J Dermatol 1997; 137: 246–50. 52. Hungerford MW. 1878. “Molly Brown.” Quoted in Bartlett J. Familiar Quotations, 14th edn. Boston, MA: Little, Brown and Company, 1968: 831b. 53. Goldsmith O. She Stoops to Conquer. Act 1. 1775. 54. Tantaro G, Ranso R, Santagata M, Santillo V. Itro A. Lower facial contouring with botulinum toxin. Type A. J Craniofac Surg 2008; 19(6): 1613–7. 55. Bertoni M, Castagna A, Baracich A, Berti G, Lazzaretti S, Morandi C. Administration of botulinum toxin after total hip replacement. Eur J Phys Rehab Med 2006; 44(6): 461–5. 56. Sahai A, Dawson C, Khan MS, Dasgupta P; GKT Botulinum Study Group. Urology 2010; 75(3): 552–7. 57. Spears RC. Efficacy of botulinum toxin type A in new persistent daily headache. Headache Pain 2008; 9(6): 405–6. 58. Yoon. H, Chung WS, Shim BS. Bottulinum toxin A for the manage- ment of vulvodynia. Int J Impot Res 2007; 19(1): 86–7.
  14. 14. 1 The minute quantities of botulinum toxin type A injected directly into its site of action (in this case, extraocular muscles) prevented systemic absorption of clinically significant amounts. Following this initial success, Schantz, now working at the University of Wisconsin, began developing botulinum toxin type A for testing in humans for Dr. Scott, focusing on purification, high potency, and pres- ervation. Because no protein drugs of this type had ever been devel- oped, the methods and requirements were novel. Schantz selected the Hall strain of Clostridium botulinum for type A toxin for production because it yielded a good quantity of high-quality toxin, which was necessary for further purification and regulatory requirements. Scott went on to successfully use the botulinum toxin type A that Schantz had produced for the treatment of strabismus and blepharospasm in humans (2).The batch of botulinum toxin type A developed by Schantz was eventually approved for human use by the U.S. Food and Drug Administration (FDA) in 1989 (Fig. 1.1) under the name Oculinum. This preparation was later acquired by Allergan Inc. and, under the name BOTOX®, has been the primary treatment for focal dystonias since the late 1980s, and, over the past decade, has become an impor- tant adjunctive treatment worldwide for adult spasticity and juvenile cerebral palsy. The FDA approved the use of BOTOX® Cosmetic in 2002 for the temporary improvement in the appearance of moderate to severe glabellar lines associated with corrugator and/or procerus muscle acidity in patients 18 to 65 years of age. SYNTHESIS, STRUCTURE, AND PRODUCTS Botulinum neurotoxins are produced by bacteria as multimeric pro- tein complexes consisting of the neurotoxin and associated hemag- glutinin and nonhemagglutinin proteins.These neurotoxin-associated proteins stabilize and protect the ∼150 kDa type A botulinum neuro- toxin from degradation in the gastrointestinal tract, as well as enhance its enzymatic activity (3,4). Different bacterial strains synthesize com- plexes that vary in size and protein composition, as well as neurotoxin serotype (5). Seven different botulinum neurotoxin serotypes (A, B, C1, D, E, F, and G) and three different sizes of protein complexes have been repor- ted in the literature. The serotype and protein complex size appear to covary, such that each serotype is associated with a specific set of com- plex sizes (Table 1.1) (5). All of the serotypes form the 300 kDa com- plex; serotypes A, B, C1, and D (hemagglutinin positive) form the 500 to 700 kDa complex and only type A forms the 900 kDa complex (6,7). When botulinum neurotoxin products are manufactured for clini- cal use, the neurotoxin complexes are isolated and purified using procedures that are specific to the manufacturer. These processes determine which, if any, of the neurotoxin-associated proteins are retained in the final product. For example, during the purification process used to manufacture the Allergan botulinum toxin type A product (henceforth identified as onabotulinumtoxinA), only the ∼900 kDa complex is retained (8,9), whereas in the purification pro- cess used to manufacture the Ipsen type A product (henceforth iden- tified as abobotulinumtoxinA), an unknown mixture of complexes are retained (10). All of the neurotoxin-associated proteins are removed in the purification and manufacture of a botulinum neuro- toxin type A product Xeomin® (U.S. nonproprietary name assigned as incobotulinumtoxinA) from Merz. This product is currently awaiting FDA approval (as of April 2010) but is available in several 1 Pharmacology, immunology, and current developments K. Roger Aoki INTRODUCTION Botulinum neurotoxins are proteins synthesized by clostridial bacteria. For clinical use, these proteins are isolated, purified, and formulated into specific products in a complex series of steps that are strictly reg- ulated by governmental agencies in most countries where the prod- ucts are approved. Because botulinum neurotoxins are derived from living organisms, they are regulated as biological products as opposed to conventional, synthetic drugs. For biological products, the method of manufacture determines not only the purity of the final product but also the reproducibility of unit activity—the dosage measurement for botulinum neurotoxins. The final formulation of the product is also critical, as this can affect product stability, efficacy, safety, and immunogenicity. This chapter discusses the history, synthesis, and structure of botuli- num neurotoxins, as well as their basic and clinical pharmacology. We also review the immunology of these proteins, our understanding of which has deepened in recent years with the identification of specific epitopes against which neutralizing antibodies are formed. Finally, we introduce several current developments in botulinum neurotoxin therapy that have broadened our view of the pharmacology of these proteins, as well as opened new avenues for clinical therapy. HISTORY Botulinum toxin type A stands alongside digitalis, atropine, and pac- litaxel as natural compounds that, although first noted for their toxic properties, are now routinely used as medicines. The recorded history of botulinum neurotoxins dates back to human encounters with improperly stored food, which caused the sickness known as botu- lism when ingested (Fig. 1.1). In the early 1800s, the German physi- cian Kerner provided one of the earliest descriptions of food poisoning caused by botulism that followed ingestion of smoked sausages (1). In the late 1800s, Professor van Ermengem, a Belgian microbiologist, iden- tified botulinum neurotoxin as the cause of botulism in a group of Belgian musicians who had eaten inappropriately prepared sausages. The events of the Second World War stimulated research and study into the activity of botulinum neurotoxins. Much of this research was conducted by Drs. Lamanna, Schantz, and colleagues at Fort Detrick, Maryland, where botulinum neurotoxin type A (BoNTA) was purified, obtained in crystalline form, and synthesized in sufficient quantities for research (Fig. 1.1) (1). A number of other investigators, including Burgen and Brooks, made much progress throughout the late 1940s and 1950s in understanding the mechanism of action of botulinum neurotoxins. By the late 1960s, the inhibitory effects of botulinum toxin type A on acetylcholine release at the neuromuscular junction had been well characterized in experimental animals (1). Working at the Smith-Kettlewell Eye Research Institute in San Francisco in the 1970s, ophthalmologist Alan Scott was investigating alternatives to surgery for his patients with strabismus, a condition of ocular misalignment. Dr. Scott believed that a substance that could chemically weaken the extraocular muscles pulling the eyes out of alignment might prove a useful alternative to surgical excision of the muscles. On the advice of a colleague, Dr. Scott contacted Professor Edward Schantz (Fig. 1.1) to ask whether he had a substance that might be used to produce such chemical denervation. Schantz sug- gested botulinum toxin type A and Scott soon reported that this protein was able to correct strabismus in an experimental model (1).
  15. 15. 2 BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE European Union countries (11). The BoNTB-based product, Myobloc®/Neurobloc® is a ∼700 kDa complex. It has been assigned the chemical name rimabotulinumtoxinB. All approved botulinum toxin- based products are assigned a unit of activity, which are specific for each product and are not interchangeable nor convertible between products. The active botulinum neurotoxin protein in all serotypes is synthesized as a single chain of approximately 150 kDa that must be nicked or cleaved by proteases in order to be active (Fig. 1.3) (12). Cleavage results in a di-chain molecule consisting of an approximately 100-kDa heavy chain and an approximately 50-kDa light chain, linked by a disulfide bond (5). The crystal structure of botulinum neurotoxin type A was first reported by Professor Raymond Stevens and colleagues (13), which confirmed many of the predictions made based on studies of physiol- ogy and pharmacology. The protein structure is flat and comprises three modules: the endopeptidase (light chain), the translocation domain (N-terminal half of the heavy chain), and the binding domain (C-terminal half of the heavy chain). The crystal structure of botulinum neurotoxin type B (BoNTB) is similar to that of BoNTA (14). Reports on the crystal structures of the light chains of botulinum neurotoxin serotypes D (BoNTD) and G (BoNTG) have provided insights into the structural details of protease substrate recognition, as described in the next section (15,16). PHARMACOLOGY Mechanism of Action Botulinum neurotoxins exert their activity through a multistep pro- cess that includes binding to nerve terminals, internalization, and inhibition of calcium-dependent neurotransmitter release (17). All neurotransmitters are calcium-dependent. This chapter focuses on recent developments in the mechanism of action of botulinum neuro- toxins, and the reader is referred to several comprehensive reviews for additional information on the basic mechanisms (18,19). Binding The heavy chain (∼100 kDa) subunit of the botulinum neurotoxin molecule binds to receptors on nerve terminal membranes, located primarily but not exclusively on cholinergic neurons (20,21). The binding of botulinum neurotoxins to nerve cell membranes has been explained via a double receptor model, in which the coreceptor Table 1.1 Neurotoxin Protein Complex Sizes Associated with Each Serotype Serotype Neurotoxin protein complex size ~300 kDa (formerly M) ~500 – 700a kDa (formerly L) ~900 kDa (formerly LL) A X X X B X X C1 X X D (HA+) X X D (HA-) X E X F X Abbreviation: HA, hemagglutinin. a HA positive. Figure 1.1 History of botulinum neurotoxin development. Neurologic effects first noted from sausage ingestion 1822 1940s BTX-A isolated, purified 1989 Strabismus, blepharo- spasm First FDA approval FDA approval for glabellar lines 2002 1960s Studies of BTX-A in animal muscle 2004 FDA approval for primary axillary hyperhidrosis Bacteria identified as cause of botulism 1895 FDA approval for cervical dystonia 20001980s and 1990s Studied for treatment of dystonias, spasticity, selected other conditions 1970s First tested in strabismus patients Figure 1.2 Professor Ed Schantz in his laboratory.
  16. 16. PHARMACOLOGY, IMMUNOLOGY, AND CURRENT DEVELOPMENTS 3 comprises a ganglioside and protein component. Botulinum neurotox- ins have long been known to interact with gangliosides (22), with the exception being BoNTD, which appears to bind to a phospholipid but not to gangliosides (23). The crystal structure of BoNTA in complex with the ganglioside cell surface coreceptor GT1b (G = ganglioside; T = trisialo-ganglioside; 1b = carbohydrate’s sequence) has recently been reported (24,25). Based on these observations, the authors sug- gested that GT1b may mediate the initial contact between the botuli- num toxin and the neuronal membrane, which would serve to greatly increase the local toxin concentration at the membrane surface, permi- tting the toxin to diffuse in the plane of the membrane and bind to its protein receptor (Fig. 1.4) (24). The protein component of the receptor for botulinum toxin type A has been identified as secretory vesicle protein synaptic vesicle protein 2 (SV2) (26,27). During exocytosis, intravesicular portions of SV2 proteins are exposed to the cytoplasm, providing an exposed surface to which BoNTA can bind (Fig. 1.5) (26,27). Additional research in neuroblastoma cells suggests that FGFR3 (fibroblast growth factor receptor-3) may also be a possible protein receptor for botulinum toxin type A (28). Synaptotagmins I and II have been identified as the protein receptors for BoNTB and BoNTG (29,30). Synaptotagmins are localized to synaptic vesicle membranes and binding of BoNTB and BoNTG to these proteins leads to their inter- nalization into neurons (30,31). The crystal structure of BoNTB in complex with synaptotagmin II has been reported (30,32). The authors observed that synaptotagmin II formed a short helix that bound to a hydrophobic groove in BoNTB and BoNTG; this bind- ing groove varied in other serotypes, supporting the serotype differ- ences in protein co-receptors (30). Translocation Following binding, botulinum neurotoxins are translocated into the neuronal cytosol via receptor-mediated endocytosis (33). There appear to be two distinct internalization processes: a rapid uptake, which may utilize the vesicle recycling system, and a slower uptake requiring hours, which may be a less specific endocytotic process. This internalization process is energy-dependent and is critical for the activity of botulinum neurotoxins (34). Upon acidification of the endosome, it is hypothe- sized that a pH-dependent change in the translocation domain of the heavy chain facilitates the translocation of the light chain into the cyto- plasmic compartment. The exact mechanism of this translocation process is not known, but it has been speculated that the heavy chain can form a pore through which the light chain can pass (33). Recent data indicates that acidification does not trigger substantial structural changes to the botulinum toxin protein as previously thought, but instead may eliminate repulsive electrostatic interactions between the translocation domain and the membrane, leading to the protein’s translocation (35). Figure 1.3 Structure of botulinum neurotoxin unnicked, inactive single-chain pro- tein (150 kDa; left) and nicked, activated di-chain protein (100-kDa and 50-kDa chains; right). COOH Heavy chain Light chain S S COOH NH2 S S S-S NH2 COOH NH2 S-S Figure 1.4 Potential binding model for botulinum toxin type A. BoNTA displayed as rainbow colored ribbon, GT1b as CPK spheres and Synt-II as a gray ribbon. (A) Free BoNTA above the cell surface displaying GT1b. (B) BoNTA bound to GT1b on the cell surface. (C) BoNTA bound to GT1b and Synt-II on the neuron surface. (D) BoNTA entering the cell through endocytosis. (E) Side view of the BoNTA along the axis of possible rotation. (F) The N-terminal domain of the translocation domain (loops 600 and 760) of the 100 Å long helixes from the translocation domain swing- ing into contact with the membrane inside the acidified endosome; it is also possible that the other end of the translocation domain make the initial contact with the membrane. Source: From Ref. 24. (A) (B) (C) (D) (E) (F)
  17. 17. 4 BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE Enzymatic Activity Once inside the cytosol, the light chain cleaves one or more of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins necessary for vesicle docking and fusion, thereby reducing exocytotic neurotransmitter release (Fig. 1.6). Each serotype cleaves a specific peptide bond on one or more of the SNARE proteins (33). The enzymatic activity of the light chain requires the presence of the intramolecular zinc. In response to reduced neurotransmitter release, neuronal sprouts appear at motor-nerve terminals and nodes of Ranvier, which have been noted within 2 days after injection of BoNTA into mammalian soleus muscles (36). These sprouts persist and become more complex (increased branching and length) for at least 50 days following intra- muscular injection of BoNTA. Sprouts may establish functional synap- tic contacts (36). However, recent evidence at the rat neuromuscular junction indicates that neurotransmitter release can be detected from Figure 1.5 Molecular model of an average SV. The model is based on space-filling models of all macromolecules at near atomic resolution. (A) Outside view of a vesicle. (B) View of a vesicle sectioned in the middle (the dark-colored membrane components represent cholesterol). (C) Model containing only synaptobrevin to show the surface density of the most abundant vesicle component. The following proteins were included (copy number in parentheses): VAMP4 (2), SNAP-29 (1), vti1a (2) Syntaxin 6 (2), other syntaxins (4), other synaptotagmins (5), other Rab proteins (15), Munc-18 (2), other transporters (2), chloride channels (2), and trimeric GTPases (2). Source: From Ref. 110. (A) (B) Trimeric GTPase Other transporter Rab Munc18 Synapsin VAMP4 SNAP29 Synaptophysin CIC3 Synaptotagmin Synaptobrevin Vti1aSNAP25 V-ATPase CSP SV2 SCAMP Syntaxin VGLUT (C)
  18. 18. PHARMACOLOGY, IMMUNOLOGY, AND CURRENT DEVELOPMENTS 5 original terminals about the time that new sprouts have established a functional synapse, and accounts for more than 80% of total acetylcho- line release (37). Eventually, exocytosis is restored, the original termi- nals recover, and the sprouts regress (38). After re-innervation is complete, the target tissue is fully functional (36) and there is no clinical indication that postbotulinum re-innervation produces func- tionally substandard synapses. However, in rats, acetylcholine release has been found to recover more slowly after multiple injections than single injections (37). If this finding were also true in humans, it may suggest a tendency for increased duration of clinical response fol- lowing multiple injections; however, this has been reported in only one study out of 44 studies of repeated injections with BoNTA (39). The dosage did not change in 22 of 44 studies, increased in 4 studies, and were not reported over time in 17 studies (39). The relevance of the preclinical observation to the clinical results remains to be determined. Figure 1.6 Mechanism of action of botulinum neurotoxins. Source: from Ref. 111. Neuromuscular junction Motor nerve terminus Synaptic vesicle SNARE proteins form complex Normal neurotransmitter release Vesicle and terminal membranes fuse Synaptic fusion complex Neurotransmitter releasedAcetylcholine Acetylcholine receptor Muscle fiber contracts Muscle cell Synaptobrevin SNAP-25 Syntaxin SNARE proteins Nerve terminus Synaptic cleft Muscle cell Botulinum toxin endocytosed Light chain cleaves specific SNARE proteins Light chain Heavy chain Botulinum toxin Type C Types A,C,E Types B,D,F,G SNARE complex does not form Membranes do not fuse Neurotransmitter not released Muscle fiber paralyzed Muscle cell (A) (B) Exposure to botulinum toxin
  19. 19. 6 BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE Lack of Retrograde Transport Unlike tetanus toxin, the active portion of the botulinum toxin protein does not undergo retrograde transport and transcytosis across neurons to exert effects in distant regions (40). However, Antonucci and col- leagues recently published a paper that appears to contradict this well- known distinction between botulinum and tetanus toxins (41–43). These authors reported retrograde transport and transcytosis of botu- linum toxin into rat brain following administration into the muscles that control whisker movements—a report that was rapidly taken up by the popular press (44) and even the Journal of the American Medical Association (45). However, the results of this study are complicated by a number of important issues (46). First, the authors used a high dose of a labora- tory preparation of BoNTA that was injected into a single site of the rat whisker pad (41). The dose used was 135 pg or approximately 450 pg/kg. By way of comparison, patients treated with onabotulinumtoxinA for cosmetic glabellar treatments typically receive approximately 20 units or 3 pg/kg administered into multiple muscles, which is ∼150-fold lower than the dose used by Antonucci and colleagues. Administration of this high dose may have triggered nonspecific uptake and could have overloaded the protein transport system of the neuron. The use of such high doses of a different type (i.e., laboratory preparation BoNTA) into a single site negates the relevance of these results in a clinical setting with humans. Over 20 years of treatment with BoNTA (onabotulinum- toxin A), of the facial area has not observed any deleterious central effects and that physicians can safely use BoNTA for therapy (47). A second issue with this study is that the authors used an incom- pletely characterized antibody to differentiate between cleaved and uncleaved SNAP-25, the key substrate for BoNTA (41). The appearance of cleaved SNAP-25 in central neurons was taken to indicate retrograde transport of the active BoNTA enzyme. That is, the authors did not attempt to directly determine the presence of BoNTA in the central neurons but rather detected a fragment of the protein known to be cleaved by the BoNTA enzyme as a measure of toxin activity in the brain. They detected this protein fragment using Western blot or immunohistochemistry. However, the inference that a positive signal in these assays indicates the presence of cleaved SNAP-25 depends on the specificity of the antibody used. Because the antibody was not well characterized, it cannot be concluded with certainty that the protein binding to it was cleaved SNAP-25. A study that attempted to directly detect botulinum toxin type A in various tissues following intramuscu- lar injection using radiolabeled neurotoxin did not find evidence of distribution into the central nervous system (48). These points represent major objections to the findings from the Antonucci et al. study. The conclusions of the study do not appear to be entirely justified and, in particular, their relevance to clinical use of botulinum neurotoxins is questionable. Nonmotor Anticholinergic Effects Botulinum neurotoxins act not only on efferent motor pathways but also on efferent autonomic efferent pathways, which also utilize acetyl- choline as a neurotransmitter. The inhibitory effects of BoNTA on autonomic nerve terminals have led to its successful use in conditions of autonomic hyperactivity such as hyperhidrosis and gustatory sweat- ing (49).Although the effects on autonomic and motor nerve terminals are thought to occur by a similar mechanism (i.e., binding, internaliza- tion, and inhibition of neurotransmitter release), the clinical effects are of longer duration in some autonomic conditions than in neuro- muscular conditions. The reason for this difference is unknown. Direct evidence from preclinical studies and indirect evidence from clinical studies indicate that BoNTA affects afferent pathways via inhibition of neural input to intrafusal fibers (49,50). Intrafusal fibers are encapsulated fibers that make up muscle spindles (Fig. 1.7), or the proprioceptive organs located among skeletal muscle fibers (extrafusal fibers). Extrafusal fibers are innervated by alpha motor neurons, whereas intrafusal fibers are innervated by gamma motor neurons and Ia sensory afferents. The inhibition of gamma motor neurons decreases activation of muscle spindles, which effectively changes the sensory afferent system by reducing the Ia traffic. Filippi and colleagues con- firmed this hypothesis by establishing that local injections of BoNTA directly reduce afferent Ia fiber traffic in rats, thereby modulating sen- sory feedback (50). Histologic support for the direct effect of BoNTA on the rat muscle spindles supported the electrophysiologic results (51). Berardelli and colleagues have examined potential clinical correlates of BoNTA’s effects on intrafusal fibers. These investigators evaluated electrophysiological variables in muscles injected for the treatment of writer’s cramp (52). In these patients, BoNTA reduced the tonic vibra- tion reflex to an even greater extent than the maximal M-wave and maximal voluntary contraction. Additionally, the tonic vibration reflex but not the other variables remained reduced in several patients whose clinical benefit persisted for 7 months. The authors speculated that suppression of the tonic vibration reflex may result from effects of the neurotoxin on intrafusal muscle fibers, causing reduced spindle inflow to the central nervous system during vibration (52). Similar effects were noted in individuals with spasticity who retained some degree of motor function (53). Combined with the preclinical findings, these results suggest that the overall effect of BoNTA therapy, at medically relevant doses, may be a combination of a direct effect on the primary nerve-end organ communication coupled with an indirect effect on the overall system. These reports utilized onobotulinumtoxinA and should not be applied to other products, as summarized below. Research documenting the effects of botulinum neurotoxins on neu- rotransmitters other than acetylcholine is accumulating, particularly as it relates to pain and urinary tract dysfunction. The current develop- ments in this area are discussed in the last section of this chapter. CLINICAL PHARMACOLOGY Differences Between Botulinum Neurotoxin Products Because botulinum neurotoxins are biological products, their clinical pharmacology depends on a variety of factors, including the bacterial strain used in production, methods of isolation and purification, sero- type, formulation, and procedures used to determine biological activ- ity (Table 1.2). These factors vary for each commercially available botulinum neurotoxin product. Each product’s distinct formulation results in a unique interaction with biologic systems following injec- tion. The system is exposed to different ingredients and different num- bers of molecules that likely influence local osmotic gradients and diffusion. Additionally, isolation and purification methods can influ- ence the antigenicity of biological products (54). Even minor changes to the formulation of biological products can influence clinical pro- file, as demonstrated with a human erythropoietin analog epoetin alfa (54). In Europe, the switch from albumin to polysorbate 80 in the formulation of one of these products [Eprex (J&J), in EU, Australia, Figure 1.7 Muscle spindle structure showing intrafusal and extrafusal fibers. Muscle spindle Extrafusal fibers Intrafusal fibers
  20. 20. PHARMACOLOGY, IMMUNOLOGY, AND CURRENT DEVELOPMENTS 7 Singapore, and Canada] led to an unpredicted increase in cases of pure red cell aplasia—a severe form of potentially lethal anemia (54–57). Additional changes to the product have since reduced cases of this nor- mally rare immunogenic response to low levels (55), but this example illustrates the complexity of biological products and the unpredictable effects of even small changes in manufacturing process or formulation. Of paramount importance with botulinum neurotoxin products is the difference in units of biological activity. Units of different botuli- num neurotoxin products are not equivalent and cannot be inter- changed using a single ratio (58,59).Not only do botulinum neurotoxin products exhibit pharmacologic differences (60,61), but they are also used clinically at different doses depending on the indication and individual presentation (62). Approved Products Even products that are labeled as containing the same number of units per vial do not necessarily exhibit the same biological activity. This was demonstrated in a recent comparison of two BoNTA products, both labelled at 100 units (63). One of the products botulinum neurotoxin A (incobotulinumtoxinA, Merz) was found to contain substantially fewer units per vial when compared against onabotulinumtoxinA reference standard (63). Additionally, units of the incobotulinumtoxinA product were substantially lower when tested one year later, which was still prior to the product’s expiration date. These results suggest product degradation over time and emphasize that attempts to interchange BoNTA products fail to take into consideration potentially critical effects of formulation on biological product performance. Many attempts have been made to compare the units of several established BONTA products (onabotulinumtoxinA and abobotuli- numtoxinA) (58,64,65). Although in the past it was reported by some investigators that these two products were clinically comparable when used at dose ratios of approximately 1:3 to 1:5, a growing body of evidence suggests that the products exhibit different clinical characteristics regardless of the dose ratio (58,66,67). In particular, abobotulinumtoxinA seems to exhibit a somewhat different side effect profile than onabotulinumtoxinA (66,68–70). This conclusion is also supported by preclinical comparisons, which are more highly contro- lled and can employ a broader range of doses than is possible in human studies (60,61). Despite these results, some authors report dose ratios as low as 1:1 (71). It should be noted that the bulk of the literature does not support this dose ratio, and it does not represent clinical practice (62). Clinical use of this dose ratio could have serious consequences for patients; for instance, use of onabotulinumtoxinA at the higher doses needed for abobotulinumtoxinA could lead to inadvertent side effects, whereas use of abobotulinumtoxinA at doses used for ona- botulinumtoxinA could lead to inadequate efficacy and duration of action. Clearly, to maximize patient safety and clinical benefit, it is critical that clinicians use each BoNTA product at doses that have been established for that specific product in the specific indication. The botulinum toxin type B (rimabotulinutoxinB, BoNTB) from Elan/Solstice also cannot be compared to other products based on a dose ratio. Doses of this product are often up to several orders of magnitude higher than onabotulinumtoxinA depending on the indication and individual patient presentation, and adverse event profiles differ (72). Unlicensed Products The case against dose conversion of botulinum neurotoxins has become even more prominent with the unscrupulous use of counter- feit and unlicensed products. One case of nonequivalent units was demonstrated with a botulinum toxin type A product CNBTX-A (Nanfeng) that was previously available in China but was not appro- ved there or in any other country (73). The label on each vial indica- ted 55 units, but the product was not accompanied by a package insert or dosing recommendations. Testing against an onabotulinumtoxinA reference standard showed that a vial of CNBTX-A contained 243 units of biological activity (73). Serious consequences could have resulted if clinicians had obtained this nonapproved product and applied it to patients based on doses of an approved product. This alarming varia- tion in biological activity strongly indicates that clinicians must not rely on dosing of one neurotoxin product to ascertain dosing of another. This finding also indicates the dangers of nonapproved neurotoxins—the lack of literature to guide dosing of this product and the lack of an approved manufacturing process could lead to serious, unintended consequences for patients. These risks were validated by the unscrupulous use of a highly con- centrated laboratory preparation of BoNTA (that occurred in 2006). This neurotoxin product, which was clearly labeled for laboratory use only, was illegally administered to several individuals in a Florida clinic for cosmetic purposes (74).All of the individuals exposed to this highly concentrated laboratory preparation of BoNTA experienced progressive muscle weakness and neuropathies, and were eventually hospitalized for up to 14 weeks (74). The dangers of using unlicensed botulinum neurotoxin prepara- tions are unambiguous: clinicians risk patient safety. It is critical that clinicians verify the botulinum neurotoxin product they are using and use it at doses recommended by the manufacturer and/or docu- mented in the published clinical literature. The data documenting the nonequivalence of botulinum neurotoxin units is summarized in Figure 1.8. Neuromuscular Injection In the clinic, BoNTA is most often injected into overactive muscles that vary depending on the condition to be treated and the patient’s individual presentation. Onset of action following intramuscular Table 1.2 Characteristics and Packaging of Different Botulinum Neurotoxin Products (11,59,108,109) Botulinum neurotoxin product (year, country of first approval) Biological units per vial Formulation Method of stabilization BOTOX® (Allergan) Onabotulinumtoxin A (1989, USA) 100 U 50 U Botulinum toxin type A 900-kDa protein 500,000 ng serum albumin 900,000 ng sodium chloride Vacuum dried Dysport® (Ipsen) Abobotulinumtoxin A (1991, UK) 500 U 300 U (USA) Botulinum toxin type A 500- and 900-kDa protein 125,000 ng serum albumin 2,500,000 ng lactose Lyophilized Xeomin® (Merz) Botulinum neurotoxin A (2005, Germany) 100 U Botulinum toxin type A 150-kDa protein 1 mg serum albumin 4.7 mg sucrose Lyophilized Myobloc® /Neurobloc® (Elan/Solstice) Rimabotulinumtoxin B (2000, USA) 2500 U, 5000 U, or 10,000 U Botulinum toxin type B 500–700-kDa protein 0.05% serum albumin 0.1 M sodium chloride 0.01 M sodium succinate Liquid formulation, pH 5.6
  21. 21. 8 BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE injection is approximately 3 to 7 days (75). The beneficial effects of each treatment with BoNTA last approximately 3 to 5 months in neu- romuscular conditions (75,76). The duration of BoNTB is somewhat shorter than that of BoNTA and has been reported as 6 to 8 weeks with 1000 units and 10 to 12 weeks with 2000 units in the management of brow or glabellar lines (75). Due to the chronic nature of most of the neuromuscular condi- tions that botulinum neurotoxins are used to treat, repeated injec- tions are typically required over the course of many years. The results of numerous studies indicate that most patients respond to BoNTA for many years without decrements in safety, responsiveness, or qual- ity of life, and without increased doses (77,78). Some studies have reported enhanced benefits with BoNTA following repeated injec- tions, showing increased duration, decreased adverse events, or greater functional improvements (e.g., gait in children with cerebral palsy) with successive injections (39). In the case of improved gait, this may be due to adaptation of the patient to reduced tone. How- ever, the increased duration and other benefits may also be due to altered sensory feedback from the periphery to the central nervous system (79). Intradermal Injection In the treatment of focal hyperhidrosis, BoNTA is injected intrader- mally instead of intramuscularly. The onset of action of BoNTA in various forms of hyperhidrosis is within 1 week, and benefits last approximately 7 months (80,81). Benefits are maintained following repeated injections for at least 16 months (80). Several studies have examined the use of BoNTB (rimabotulinum- toxinB) for axillary hyperhidrosis. These studies have found that type B significantly reduces sweating, but with distal autonomic side effects that are not observed with type A such as visual accommodation diffi- culties and dry mouth (82). IMMUNOLOGY Like most foreign proteins introduced into the body, botulinum neuro- toxins can be antigenic and, under the certain circumstances (e.g. dose and frequency), elicit immune responses designed to inactivate the protein. Only antibodies directed against the 150-kDa neurotoxin neutralize its activity (83). Antibodies may occasionally be formed against the nontoxin proteins in the botulinum neurotoxin complex, but these do not affect clinical responsiveness (83). Within the BoNTA molecule, antibodies directed against certain peptides within amino acid residues 449 to 1296 of the heavy chain are neutralizing (83). Nearly all of the regions overlap or coincide with the regions on the protein that bind to synaptosomes (84), providing a physical basis for their neutralizing effect (i.e., blocking the binding of BoNTA to the nerve terminal). Similar results have been found for BoNTB (rimabotulinumtoxinB) (85). Research has further shown that the pattern of antibody recognition varies among patients with neu- tralizing antibodies, such that not all patients develop antibodies to the same portion of the BoNTA molecule (84). These findings under- score the role of individual genetic factors in neutralizing antibody development. In addition to individual genetic factors, manufacturing methods and formulation are known to affect the immunogenicity of biological products (54,86), and thus, it cannot be assumed that the rate of neu- tralizing antibody formation will be the same with all botulinum neuro- toxin products. Both short-term and long-term (e.g. 2-year) studies are needed with each individual product to adequately determine its anti- genicity in a given clinical population at relevant doses. Few studies have been published on the antigenicity of botulinum neurotoxin preparations in cosmetic use, partly because the relatively low doses utilized minimize the potential for neutralizing antibody formation. In a short-term spasticity study and a long-term cervical dystonia study, the rate of neutralizing antibody formation with ona- botulinumtoxinA (Allergan) has been documented at approximately 1% (87,88). In these studies, the sera of all available patients were ana- lyzed using the mouse protection assay, which is the gold standard test due to its specificity, despite its relative lack of sensitivity. Abobotu- linumtoxinA (Ipsen) did not elicit any antibody formation in a short- term spasticity study (89); however, in a longer-term study of 93 dystonia patients who received a mean of 4 treatments (range 1–13), the overall rate of neutralizing antibody formation was 3% (4% among cervical dystonia patients) (90). The neutralizing antibody formation rate with incobotulinumtoxinA (Merz) has not been reported. The neutralizing antibody formation rate with rimabotulinumtoxintyptB (Solstice) has been reported as 10% after 1 year or 18% after 18 months of treatment for cervical dystonia (91). Figure 1.8 Units of different botulinum neurotoxin preparations are not equivalent (see text for references). Unapproved, unlicensed preparations Approved, licensed preparations BOTOX® Reference product in nearly all unit activity comparison studies Dysport® No single ratio adequate to convert from BOTOX® doses; adverse event profile somewhat different from BOTOX® Myobloc® Botulinum toxin type B; clinical doses much higher than for the type A preparations Xeomin® Different unit activity from BOTOX® in preclinical tests CNBTX-A Vial labeled 55 units; actual bioactivity in Allergan unit assay 243 units Laboratory preparations Can be exceedingly potent; not for human use; patients hospitalized following injection for cosmetic purposes Patient safety is at risk if clinicians use unlicensed preparations Each approved product should be used at doses recommended by the manufacturer or documented in the clinical literature
  22. 22. PHARMACOLOGY, IMMUNOLOGY, AND CURRENT DEVELOPMENTS 9 Primary or secondary clinical nonresponsiveness has been reported in the absence of neutralizing antibodies, suggesting that there may be other reasons for lack of response to botulinum neurotoxins. These reasons include patient perception (e.g., subsequent injections may appear to have a less dramatic effect than the first) (92), either because patients continue to experience some benefit from the previ- ous injection or perhaps due to lack of memory about the severity of their condition prior to injection. The injections may not be directed into the optimal muscles or the muscles involved may have changed from the previous visit either due to progression of the disorder or neural adaptation (93). These changes may require a modification of injection sites, dose, or both in order to maintain optimal treatment benefit. CURRENT DEVELOPMENTS Several interesting developments are currently taking place in botuli- num neurotoxin therapy. The first concerns the activity of these pro- teins in the treatment of pain and the second is the novel information on mechanism of action and clinical benefit derived from the appli- cation of these proteins on urinary tract disorders such as overactive bladder and benign prostatic hypertrophy. Pain Beneficial effects of BoNTA on pain were stimulated by the finding that injections into patients with cervical dystonia relieved not only the aberrant muscle activity, but also the associated neck and shoulder pain (94). The benefits reported for BoNTA in chronic migraine (95) and the lack of direct concordance between its effects on muscle relax- ation and improvement in pain in neuromuscular conditions (96) suggest that pain relief may not be strictly secondary to the reduction of muscle contractions. This has led to an increase in research direc- ted at identifying possible mechanisms by which BoNTA may act to reduce pain. Pain is transmitted to the central nervous system by two types of afferent nerves or primary nociceptive afferents: A-delta fibers that mediate sharp, pricking pain and C fibers that mediate slow, burning pain. The cell bodies of these neurons are located in the dorsal root ganglia, where they send out a single process that branches to innervate the periphery as free nerve endings (nociceptors—pain sensory organs) and the other to innervate the central nervous system, synapsing on neurons in the dorsal horn of the spinal cord. Pain sensations detected in the face and head are transmitted by trigeminal neurons (A delta and C fibers) whose cell bodies are located in the trigeminal ganglion and whose axons synapse in the brain stem. Type C fibers release sub- stance P, somatostatin, and other neuropeptides from both central and peripheral terminals. These peptides mediate pain and inflam- matory reactions. BoNTA has been found to inhibit substance P release from cultured dorsal root ganglion neurons (97).Substance P is a peptide neurotrans- mitter released by primary nociceptive afferents (C fibers). Addition- ally, botulinum toxin type A has been found to reduce the stimulated but not basal release of calcitonin gene-related peptide (CGRP) from cultured trigeminal ganglia neurons (98). CGRP is an inflammatory neuropeptide that is contained within dorsal root ganglia neurons and colocalized with substance P in most trigeminal and other sensory ganglia neurons. BoNTA inhibits the release of acetylcholine from both alpha and gamma motor neurons, thus eliciting muscle relax- ation. Additionally, BoNTA has antinociceptive effects in several ani- mal models (99,100). A possible mechanism by which BoNTA may act in reducing pain through inhibition of pain neuropeptides, direct reduction of peripheral sensitization of the pain nerve, and therefore indirect reduction of central sensitization associated with chronic pain (Fig. 1.9). Beneficial effects of BoNTA on pain associated with postherpetic neuralgia was reported in several case studies in 2002 (101). A recent randomized, controlled study has confirmed these effects in patients with neuropathic pain due to postherpetic neuralgia or focal nerve injury accompanied by spontaneous pain and mechanical allodynia (Fig. 1.10) (102). Results of this study indicated that BoNTA was more effective than placebo at reducing spontaneous pain intensity, which correlated with the preservation of thermal sensation at baseline (102). BoNTA also improved allodynia and decreased cold pain threshold, without affecting perception thresholds. Neuropathic symptoms and general activity also significantly improved in these patients, and injec- tions were well tolerated. The authors concluded that BoNTA may induce direct analgesic effects in patients with chronic neuropathic pain independent of its effects on muscle tone. These findings suggest that BoNTA may be a useful treatment for certain types of neuropathic pain that include a neurogenic inflammatory mechanism. Some chronic pain conditions include postherpetic neuralgia, painful dia- betic neuropathy, complex regional pain syndrome, chronic migraine, overactive bladder (see below), arthritis, etc. Studies examining the effects of these proteins in other conditions characterized by a promi- nent pain component are ongoing. Figure 1.9 Possible mechanism of botulinum neurotoxin inhibition of pain. Botulinum toxin type A may directly inhibit primary sensory fibers, leading to a reduction of peripheral sensitization, and an indirect reduction in central sensitization, receptor field expansion, and allodynia. Abbreviations: CNS, central nervous system; CGRP, calcitonin gene related peptide; TRPV1, transient receptor potential cation channel, subfamily V, member 1 (i.e. capsaicin receptor); c-Fos, a protein produced by the proto-oncogene of the immediate early gene family of transcription factors. Peripheral stimulation Prevents: • Release of glutamate, CGRP, SP • Peripheral sensitization • Formalin P-II pain • (TRPV1 expression) Antidromic activation CNS Botulinum toxin/A Indirectly prevents: • Central sensitization • Inhibits c-Fos • Receptor field expansion • Allodynia Additional activation Clinical relevance of these preclinical results remain to be established X Release of glutamate and peptides in CNS
  23. 23. 10 BOTULINUM TOXINS IN CLINICAL AESTHETIC PRACTICE Lower Urinary Tract Disorders BoNTA is an effective therapy for the treatment of overactive bladder, as demonstrated by a recent European consensus report that concluded that “the use of botulinum neurotoxin type A (BoNTA) is recom- mended in the treatment of intractable symptoms of neurogenic detrusor overactivity (NDO) or idiopathic detrusor overactivity (IDO) in adults (grade A)” (103). When injected into the bladder, BoNTA reduces acetylcholine release from parasympathetic cholinergic fibers that innervate the detrusor muscle, leading to muscle relaxation. In addition to these motor effects, Figure 1.11 Proposed mechanism of action of botulinum toxin type A (BoNTA) injected into the overactive bladder wall. It has been proposed that a complex system of inter- actions exists between the release of neurotransmitters and actions on respective receptors located on the urothelium and suburothelium, corresponding to pathways of bladder mechanosensation. All connections identified by arrows are thought to be upregulated in detrusor overactivity. BoNTA may exert a multimodal effect on those pathways via multiple inhibition of the vesicular release of neurotransmitters and neuropeptides by the urothelium and suburothelial nerves and reduction of the axonal expression of SNARE (soluble N-ethylmaleimide-sensitive factor attachment receptor)-complex-dependent proteins that are thought to be involved in bladder mechanosensation. bl, basal lamina of urothelium; mf, myofibroblast layer; det, detrusor muscle; TRPV1, transient receptor potential vanilloid 1; P2X3, ionotropic purinergic receptor type 3; P2Y, metabotropic purinergic receptors; M2/M3, muscarinic acetylcholine receptors types 2 and 3; NK1, neurokinin receptor type 1 (SP receptor); SP, substance P; NGF, nerve growth factor; ACh, acetylcholine; ATP, adenosine triphosphate. Source: From Ref. 103. Urine (pH changes, temperature changes, mechanical stretch) TRPV1 TRPV1TRPV1 TRPV1 TRPV1 SP M3M3M2 M2 M2 M2 M2 M2 bl mf det P2X3 P2X3 Ach ACh Ach P2X3 P2X3 ATP NGFNGF ATP P2Y P2Y P2X3 NK-1 NK-1 TRPV1 M3 M3 SPTRPV1 ATP SP ATP/ACh Figure 1.10 Mean improvement in pain intensity (visual analog scale) in patients with neuropathic pain. Results from a randomized, double-blind, placebo-controlled trial of 29 patients (n = 15 botulinum toxin type A [BoNTA], n = 14 placebo) (102). 0 10 20 30 40 50 60 70 80 Baseline Week 4 Week 12 Week 24 Meanpainscore(visualanalogscale) BoNTA Placebo * * *