Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal]1Front
................................................................................................................................................................................................................
1Cover
.......................................................................................................................................................................................................
2Preface
....................................................................................................................................................................................................
3Preface to the Online Edition
........................................................................................................................................................
4Copyright Information
.......................................................................................................................................................................
5Contributors
...........................................................................................................................................................................................
13Contents
..............................................................................................................................................................................................
15I. General Principles
.......................................................................................................................................................................
151. Drug Invention & the Pharmaceutical Industry
..............................................................................................................
302. Pharmacokinetics: The Dynamics of Drug Absorption,
Distribution, Metabolism & Elimination ............. 623.
Pharmacodynamics: Molecular Mechanisms of Drug Action
..................................................................................
984. Drug Toxicity & Poisoning
.......................................................................................................................................................
1215. Membrane Transporters & Drug Response
..................................................................................................................
1566. Drug Metabolism
.....................................................................................................................................................................
1817. Pharmacogenetics
..................................................................................................................................................................
206II. Neuropharmacology
..............................................................................................................................................................
2068. Neurotransmission: The Autonomic & Somatic Motor Nervous
Systems .......................................................
2589. Muscarinic Receptor Agonists & Antagonists
..............................................................................................................
27710. Anticholinesterase Agents
.................................................................................................................................................
29611. Agents Acting at the Neuromuscular Junction & Autonomic
Ganglia
.............................................................
32412. Adrenergic Agonists & Antagonists
................................................................................................................................
38113. 5-Hydroxytryptamine (Serotonin) & Dopamine
........................................................................................................
41814. Neurotransmission & the Central Nervous System
...............................................................................................
45315. Drug Therapy of Depression & Anxiety Disorders
..................................................................................................
46516. Pharmacotherapy of Psychosis & Mania
....................................................................................................................
50017. Hypnotics & Sedatives
.......................................................................................................................................................
52418. Opioids, Analgesia & Pain Management
....................................................................................................................
58119. General Anesthetics & Therapeutic Gases
................................................................................................................
62320. Local Anesthetics
..................................................................................................................................................................
64421. Pharmacotherapy of the Epilepsies
..............................................................................................................................
68022. Treatment of Central Nervous System Degenerative Disorders
......................................................................
70723. Ethanol & Methanol
.............................................................................................................................................................
73324. Drug Addiction
........................................................................................................................................................................
762III. Modulation of Cardiovascular Function
...............................................................................................................
76225. Regulation of Renal Function & Vascular Volume
.................................................................................................
81826. Renin & Angiotensin
............................................................................................................................................................
84627. Treatment of Myocardial Ischemia & Hypertension
...............................................................................................
88928. Pharmacotherapy of Congestive Heart Failure
.......................................................................................................
91429. Anti-Arrhythmic Drugs
.........................................................................................................................................................
94030. Blood Coagulation & Anticoagulant, Fibrinolytic &
Antiplatelet Drugs
........................................................... 97931.
Drug Therapy for Hypercholesterolemia & Dyslipidemia
....................................................................................
1012IV. Inflammation, Immunomodulation & Hematopoiesis
..............................................................................
101232. Histamine, Bradykinin & Their Antagonists
............................................................................................................
104333. Lipid-Derived Autacoids: Eicosanoids &
Platelet-Activating Factor
............................................................
106734. Anti-inflammatory, Antipyretic & Analgesic Agents;
Pharmacotherapy of Gout ......................................
111435. Immunosuppressants, Tolerogens & Immunostimulants
...................................................................................
114036. Pulmonary Pharmacology
..............................................................................................................................................
117937. Hematopoietic Agents: Growth Factors, Minerals &
Vitamins
........................................................................
1224V. Hormones & Hormone Antagonists
........................................................................................................................
122438. Introduction To Endocrinology: The Hypothalamic-Pituitary
Axis
.................................................................
124939. Thyroid & Anti-Thyroid Drugs
.......................................................................................................................................
129240. Estrogens & Progestins
...................................................................................................................................................
133541. Androgens
.............................................................................................................................................................................
135142. ACTH, Adrenal Steroids & Pharmacology of the Adrenal
Cortex
.................................................................
137843. Endocrine Pancreas & Pharmacotherapy of Diabetes
Mellitus & Hypoglycemia ..................................
141344. Agents Affecting Mineral Ion Homeostasis & Bone
Turnover
.........................................................................
1449VI. Drugs Affecting Gastrointestinal Function
......................................................................................................
144945. Pharmacotherapy of Gastric Acidity, Peptic Ulcers &
Gastroesophageal Reflux Disease ................ 146746. Treatment
of Disorders of Bowel Motility & Water Flux;
..................................................................................
149847. Pharmacotherapy of Inflammatory Bowel Disease
............................................................................................
1508VII. Chemotherapy of Microbial Diseases
..............................................................................................................
150848. General Principles of Antimicrobial Therapy
.........................................................................................................
153049. Chemotherapy of Malaria
..............................................................................................................................................
156350. Chemotherapy of Protozoal Infections: Amebiasis, Giard
...............................................................................
159651. Chemotherapy of Helminth Infections
......................................................................................................................
162552. Sulfonamides, Trimethoprim-Sulfamethoxazole, Quinolone
..........................................................................
164653. Penicillins, Cephalosporins & Other Beta-Lactam
Antibiotics
........................................................................
167154. Aminoglycosides
................................................................................................................................................................
169355. Protein Synthesis Inhibitors & Miscellaneous
Antibacterial Agents
.............................................................
172856. Chemotherapy of Tuberculosis, Mycobacterium Avium Complex
Disease & Leprosy ....................... 175557. Antifungal
Agents
...............................................................................................................................................................
178558. Antiviral Agents (Nonretroviral)
....................................................................................................................................
181659. Antiretroviral Agents & Treatment of HIV Infection
.............................................................................................
1845VIII. Chemotherapy of Neoplastic Diseases
.........................................................................................................
184560. General Principles of Cancer Chemotherapy
.......................................................................................................
185461. Cytotoxic Agents
................................................................................................................................................................
191662. Targeted Therapies: Tyrosine Kinase Inhibitors, Monoclonal
Antibodies & Cytokines ........................ 194663. Natural
Products in Cancer Chemotherapy: Hormones & Related Agents
.............................................. 1961IX. Special
Systems Pharmacology
.............................................................................................................................
196164. Ocular Pharmacology
......................................................................................................................................................
199365. Dermatological Pharmacology
.....................................................................................................................................
202566. Contraception & Pharmacotherapy of Obstetrical &
Gynecological Disorders ......................................
204767. Environmental Toxicology: Carcinogens & Heavy Metals
...............................................................................
2075X. Appendices
................................................................................................................................................................................
2075I. Principles of Prescription Order Writing & Patient
Compliance
........................................................................
2087II. Design & Optimization of Dosage Regimens:
Pharmacokinetic Data
..........................................................
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
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Preface
The publication of the twelfth edition of this book is a testament
to the vision and ideals of the original authors, Alfred Gilman and
Louis Goodman, who, in 1941 set forth the principles that have
guided the book through eleven editions: to correlate pharmacology
with related medical sciences, to reinterpret the actions and uses
of drugs in light of advances in medicine and the basic biomedical
sciences, to emphasize the applications of pharmacodynamics to
therapeutics, and to create a book that will be useful to students
of pharmacology and to physicians. These precepts continue to guide
the current edition.
As with editions since the second, expert scholars have contributed
individual chapters. A multiauthored book of this sort grows by
accretion, posing challenges to editors but also offering memorable
pearls to the reader. Thus, portions of prior editions persist in
the current edition, and I hasten to acknowledge the contributions
of previous editors and authors, many of whom will see text that
looks familiar. However, this edition differs noticeably from its
immediate predecessors. Fifty new scientists, including a number
from outside the U.S., have joined as contributors, and all
chapters have been extensively updated. The focus on basic
principles continues, with new chapters on drug invention,
molecular mechanisms of drug action, drug toxicity and poisoning,
principles of antimicrobial therapy, and pharmacotherapy of
obstetrical and gynecological disorders. Figures are in full color.
The editors have continued to standardize the organization of
chapters; thus, students should easily find the basic physiology,
biochemistry, and pharmacology set forth in regular type; bullet
points highlight important lists within the text; the clinician and
expert will find details in extract type under clear
headings.
Online features now supplement the printed edition. The entire
text, updates, reviews of newly approved drugs, animations of drug
action, and hyperlinks to relevant text in the prior edition are
available on the Goodman & Gilman section of McGraw-Hill's
websites, AccessMedicine.com and AccessPharmacy.com. An Image Bank
CD accompanies the book and makes all tables and figures available
for use in presentations.
The process of editing brings into view many remarkable facts,
theories, and realizations. Three stand out: the invention of new
classes of drugs has slowed to a trickle; therapeutics has barely
begun to capitalize on the information from the human genome
project; and, the development of resistance to antimicrobial
agents, mainly through their overuse in medicine and agriculture,
threatens to return us to the pre-antibiotic era. We have the
capacity and ingenuity to correct these shortcomings.
Many, in addition to the contributors, deserve thanks for their
work on this edition; they are acknowledged on an accompanying
page. In addition, I am grateful to Professors Bruce Chabner
(Harvard Medical School/Massachusetts General Hospital) and Björn
Knollmann (Vanderbilt University Medical School) for agreeing to be
associate editors of this edition at a late date, necessitated by
the death of my colleague and friend Keith Parker in late 2008.
Keith and I worked together on the eleventh edition and on planning
this edition. In anticipation of the editorial work ahead, Keith
submitted his chapters before anyone else and just a few weeks
before his death; thus, he is well represented in this volume,
which we dedicate to his memory.
Laurence L. Brunton San Diego, California December 1, 2010
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
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Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12th Edition Preface to the Online Edition
The first edition of Goodman & Gilman's The Pharmacological
Basis of Therapeutics was published in 1941. Medicine has changed
dramatically since then; so, too, has the delivery of information.
The editors of the online version of 12th edition of Goodman &
Gilman are hoping to be at the forefront of publishing technology
in a project to enhance the premier text in pharmacology and bring
it to your desktop. We hope to bring not just the text of the book
but to enhance the text with additional features. The production of
on-line resources for Goodman & Gilman will be guided by three
complementary priorities:
1. To provide regular updates, particularly in areas of
pharmacology and therapeutics where significant advances in basic
or clinical research have occurred since publication of the printed
version
2. To provide faculty and students with high-quality electronic
resources to enhance teaching and learning of pharmacology
3. To provide comprehensive search results that allow users quick
access to required content
We are currently working on the following online resources to
enhance the 12th edition of Goodman & Gilman:
Updates: Regular updates, including new chapter content, a Clinical
Pharmacist's Corner that discusses newly approved drugs or new
therapeutic uses of approved drugs, and pieces that focus on
emerging areas of pharmacological interest Grand Rounds: Occasional
webcasts of lectures in areas of therapeutic importance by
authorities Multimedia Content: To complement the text, we have
started an ongoing series of interactive, animated versions of some
of the more important figures from Goodman & Gilman, which are
useful for interactive self-study by students
The Editors of Goodman & Gilman welcome your thoughts on
improvements and corrections to the text, as well as suggestions
and submissions for online updates. If you are a pharmacologist,
pharmacist, physician, or medical scientist and you would are
interested to contribute an update, please send an email to the
Editors at
[email protected].
The ENIAC (Electronical Numerical Integrator and Computer; circa
1945) was the first electronic computer. The invention of Dr. J. W.
Mauchly and Mr. J. Presper Eckert, it containied close to 18,000
vacuum tubes, occupied a room 30 by 50 feet, weighed 30 tons and
cost of more than $486,000. It was used at the War Department's
Ballistics Research Laboratory to calculate artillery trajectories.
(U.S. Army Photo, courtesy of
http://ftp.arl.army.mil/~mike/comphist/ and
http://ftp.arl.army.mil/ftp/historic- computers/.)
1st Edition Table of Contents
Page 1
Page 2
Page 3
Page 4
Page 5
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
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Copyright Information
Goodman and Gilman's The Pharmacological Basis of Therapeutics,
Twelfth Edition Copyright © 2011, 2006, 2001, 1996, 1990, 1985,
1980, 1975, 1970, 1965, 1955, 1941 by The McGraw-Hill Companies,
Inc. All rights reserved. Printed in China. Except as permitted
under the United States Copyright Act of 1976, no part of this
publication may be reproduced or distributed in any form or by any
means, or stored in a database or retrieval system, without the
prior written permission of the publisher.
ISBN 978-0-07-162442-8 MHID 0-07-162442-2
Notice Medicine is an ever-changing science. As new research and
clinical experience broaden our knowledge, changes in treatment and
drug therapy are required. The authors and the publisher of this
work have checked with sources believed to be reliable in their
efforts to provide information that is complete and generally in
accord with the standards accepted at the time of publication.
However, in view of the possibility of human error or changes in
medical sciences, neither the authors nor the publisher nor any
other party who has been involved in the preparation or publication
of this work warrants that the information contained herein is in
every respect accurate or complete, and they disclaim all
responsibility for any errors or omissions or for the results
obtained from use of the information contained in this work.
Readers are encouraged to confirm the information contained herein
with other sources. For example and in particular, readers are
advised to check the product information sheet included in the
package of each drug they plan to administer to be certain that the
information contained in this work is accurate and that changes
have not been made in the recommended dose or in the
contraindications for administration. This recommendation is of
particular importance in connection with new or infrequently used
drugs.
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Copyright Information
4 / 2136
Contributors
Editor Laurence L. Brunton, PhD Professor of Pharmacology and
Medicine School of Medicine, University of California, San Diego La
Jolla, California
Associate Editors Bruce A. Chabner, MD Professor of Medicine
Harvard Medical School Director of Clinical Research Massachusetts
General Hospital Cancer Center Boston, Massachusetts
Björn C. Knollmann, MD, PhD Professor of Medicine and Pharmacology
Oates Institute for Experimental Therapeutics Division of Clinical
Pharmacology Vanderbilt University School of Medicine Nashville,
Tennessee
Contributors (print) Edward P. Acosta, PharmD Professor of Clinical
Pharmacology University of Alabama, Birmingham
Peter J. Barnes, DM, DSc, FRCP, FMedSci, FRS Professor and Head of
Respiratory Medicine National Heart & Lung Institute Imperial
College, London
Jeffrey A. Barnes, MD, PhD Fellow in Hematology-Oncology
Dana-Farber Cancer Institute Boston, Massachusetts
Leslie Z. Benet, PhD Professor of Bioengineering and Therapeutic
Sciences Schools of Pharmacy and Medicine University of California,
San Francisco
John E. Bennett, MD Chief of Clinical Mycology National Institute
of Allergy and Infectious Diseases Bethesda, Maryland
William Bennett, MD Professor (Emeritus) of Medicine and
Pharmacology Oregon Health & Science University, Portland
Thomas P. Bersot, MD, PhD Professor of Medicine; Associate
Investigator Gladstone Institute of Cardiovascular Disease
University of California, San Francisco
Joseph R. Bertino, MD Professor of Medicine and Pharmacology Robert
Wood Johnson Medical School University of Medicine & Dentistry
of New Jersey New Brunswick
Donald K. Blumenthal, PhD Associate Professor of Pharmacology &
Toxicology College of Pharmacy University of Utah, Salt Lake
City
Viengngeun Bounkeua, PhD Medical Scientist Training Program, School
of Medicine University of California, San Diego
Gregory A. Brent, MD Professor of Medicine and Physiology Geffen
School of Medicine University of California, Los Angeles
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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University of California, Los Angeles
Joan Heller Brown, PhD Professor and Chair of Pharmacology
University of California, San Diego
Craig N. Burkhart, MD Assistant Professor of Dermatology, School of
Medicine University of North Carolina, Chapel Hill
Iain L. O. Buxton, PharmD Professor of Pharmacology University of
Nevada School of Medicine, Reno
Michael C. Byrns, PhD Fellow in Pharmacology University of
Pennsylvania School of Medicine, Philadelphia
William A. Catterall, PhD Professor and Chair of Pharmacology
University of Washington School of Medicine, Seattle
Bruce A. Chabner, MD Professor of Medicine, Harvard Medical School
Director of Clinical Research, Massachusetts General Hospital
Cancer Center Boston, Massachusetts
Henry F. Chambers, MD Professor of Medicine and Chief of Infectious
Diseases San Francisco General Hospital University of California,
San Francisco
Jérôme Clain, PharmD, PhD Research Fellow in Microbiology and
Immunology College of Physicians and Surgeons Columbia University,
New York
James M. Cleary MD, PhD Attending Physician Dana-Farber Cancer
Institute Boston, Massachusetts
Michael W.H. Coughtrie, PhD Professor of Biochemical Pharmacology
Division of Medical Sciences University of Dundee, Scotland
David D'Alessio, MD Professor of Endocrinology and Medicine
University of Cinncinnati, Ohio
Richard T. Eastman, PhD Fellow in Microbiology Columbia University,
New York
Ervin G. Erdös, MD Professor (Emeritus) of Pharmacology University
of Illinois-Chicago
David A. Fidock, PhD Associate Professor of Microbiology and
Medicine College of Physicians and Surgeons Columbia University,
New York
Garret A. FitzGerald, MD Professor of Medicine, Pharmacology and
Translational Medicine and Therapeutics Chair of Pharmacology
University of Pennsylvania School of Medicine, Philadelphia
Charles W. Flexner, MD Professor of Medicine, Pharmacology and
Molecular Sciences, and International Health The Johns Hopkins
University School of Medicine and Bloomberg School of Public Health
Baltimore, Maryland
Peter A. Friedman, PhD Professor of Pharmacology and Chemical
Biology School of Medicine University of Pittsburgh,
Pennsylvania
John W. Funder, AO, MD, BS, PhD, FRACP Professor of Medicine,
Prince Henry's Institute
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Professor of Medicine, Prince Henry's Institute Monash Medical
Centre ClaytonVictoria, Australia
James C. Garrison, PhD Professor of Pharmacology, School of
Medicine University of Virginia, Charlottesville
Kathleen M. Giacomini, PhD Professor and Chair of Biopharmaceutical
Sciences School of Pharmacy University of California, San
Francisco
Alfred G. Gilman, MD, PhD Professor (Emeritus) of Pharmacology
University of Texas Southwestern Medical School Chief Scientific
Officer, Cancer Prevention and Research Institute of Texas,
Dallas
Lowell A. Goldsmith, MD, MPH Professor of Dermatology, School of
Medicine University of North Carolina, Chapel Hill, North
Carolina
Frank J. Gonzalez, PhD Chief, Laboratory of Metabolism Center for
Cancer Research, National Cancer Institute Bethesda, Maryland
Tilo Grosser, MD Assistant Professor of Pharmacology Institute for
Translational Medicine and Therapeutics University of Pennsylvania,
Philadelphia
Tawanda Gumbo, MD Associate Professor of Internal Medicine
University of Texas Southwestern Medical School, Dallas
Stephen R. Hammes, MD, PhD Professor of Medicine, Chief of
Endocrinology and Metabolism School of Medicine and Dentistry
University of Rochester, New York
R. Adron Harris, PhD Professor of Molecular Biology; Director,
Waggoner Center for Alcohol and Addiction Research University of
Texas, Austin
Lisa A. Hazelwood, PhD Research Fellow, Molecular Neuropharmacology
Section National Institute of Neurological Disorders and Stroke
Bethesda, Maryland
Jeffrey D. Henderer, MD Professor and Chair of Ophthalmology Temple
University School of Medicine Philadelphia, Pennsylvania
Ryan E. Hibbs, PhD Research Fellow, Vollum Institute Oregon Health
& Science University, Portland
Randa Hilal-Dandan, PhD Lecturer in Pharmacology University of
California, San Diego
Brian B. Hoffman, MD Professor of Medicine, Harvard Medical School
Physician, VA-Boston Health Care System Boston, Massachusetts
Peter J. Hotez, MD, PhD Professor and Chair of Microbiology,
Immunology, and Tropical Medicine George Washington University
Washington, DC
Nina Isoherranen, PhD Assistant Professor of Pharmaceutics, School
of Pharmacy University of Washington, Seattle
Edwin K. Jackson, PhD Professor of Pharmacology and Chemical
Biology School of Medicine University of Pittsburgh,
Pennsylvania
Allen P. Kaplan, MD Clinical Professor of Medicine
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Clinical Professor of Medicine Medical University of South
Carolina, Charleston
Robert S. Kass, PhD Professor and Chair of Pharmacology Vice Dean
for Research College of Physicians and Surgeons Columbia
University, New York
Kenneth Kaushansky, MD Dean, School of Medicine and Senior Vice
President of Health Sciences SUNY Stony Brook, New York
Thomas J. Kipps, MD, PhD Professor of Medicine, Moores Cancer
Center University of California, San Diego
Ronald J. Koenig, MD, PhD Professor of Metabolism, Endocrinology
and Diabetes Department of Internal Medicine University of Michigan
Health System, Ann Arbor
Alan M. Krensky, MD Senior Investigator, National Cancer Institute,
Bethesda, Maryland
Nora Laiken, PhD Lecturer in Pharmacology and Medicine University
of California, San Diego
Andrew A. Lane, MD, PhD Fellow, Dana-Farber Cancer Institute
Massachusetts General Hospital Cancer Center, Boston
Richard J. Lee, MD, PhD Professor of Medicine, Harvard Medical
School Physician, Massachusetts General Hospital Boston,
Massachusetts
Ellis R. Levin, MD Professor of Medicine; Chief of Endocrinology
Diabetes and Metabolism University of California, Irvine, and Long
Beach VA Medical Center, Long Beach
Dan L. Longo, MD Scientific Director, National Institute on Aging
National Institutes of Health, Bethesda, Maryland
Alex Loukas, PhD Professor of Public Health, Tropical Medicine and
Rehabilitation Sciences James Cook University, Cairns,
Australia
Conan MacDougall, PharmD, MAS Associate Professor of Clinical
Pharmacy School of Pharmacy University of California, San
Francisco
Kenneth P. Mackie, MD Professor of Neuroscience Indiana University,
Bloomington
Bradley A. Maron, MD Fellow in Cardiovascular Medicine Harvard
Medical School and Brigham and Women's Hospital Boston,
Massachusetts
James McCarthy, MD Associate Professor of Clinical Tropical
Medicine University of Queensland Brisbane, Australia
James O. McNamara, MD Professor and Chair of Neurobiology Director
of Center for Translational Neuroscience Duke University Medical
Center Durham, North Carolina
Jonathan M. Meyer, MD Assistant Adjunct Professor of Psychiatry
University of California, San Diego
Thomas Michel, MD, PhD Professor of Medicine and Biochemistry
Harvard Medical School Senior Physician in Cardiovascular Medicine
Brigham and Women's Hospital
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Senior Physician in Cardiovascular Medicine Brigham and Women's
Hospital Boston, Massachusetts
S. John Mihic, PhD Professor of Neurobiology Waggoner Center for
Alcohol & Addiction Research Institute for Neuroscience and
Cell & Molecular Biology University of Texas, Austin
Constantine S. Mitsiades, MD, PhD Professor of Medical Oncology
Dana-Farber Cancer Institute, Harvard Medical School Boston,
Massachusetts
Perry Molinoff, MD Professor of Pharmacology, School of Medicine
University of Pennsylvania, Philadelphia
Dean S. Morrell, MD Associate Professor of Dermatology University
of North Carolina, Chapel Hill
Beverly Moy, MD, MPH Assistant Professor of Medicine Harvard
Medical School Massachusetts General Hospital, Needham
Hamza Mujagic, MD, MR. SCI, DR. SCI Visiting Professor of
Hematology and Oncology Harvard Medical School Massachusetts
General Hospital, Needham
Joel W. Neal, MD, PhD Assistant Professor of Medicine-Oncology,
Stanford University School of Medicine, Palo Alto, California
Charles P. O'Brien, MD, PhD Professor of Psychiatry, School of
Medicine University of Pennsylvania, Philadelphia
James O'Donnell, PhD Professor of Behavioral Medicine and
Psychiatry School of Medicine West Virginia University,
Morgantown
Erin M. Olson, MD Fellow in Medical Oncology Dana-Farber Cancer
Institute Boston, Massachusetts
Taylor M. Ortiz, MD Clinical Fellow in Medical Oncology Dana-Farber
Cancer Institute General Hospital Cancer Center Boston,
Massachusetts
Kevin Osterhoudt, MD, MSCE, FAAP, FACMT Associate Professor of
Pediatrics School of Medicine, University of Pennsylvania Medical
Director, Poison Control Center, Children's Hospital of
Philadelphia, Pennsylvania
Keith L. Parker, MD, PhD (deceased) Professor of Internal Medicine
and Pharmacology Chief of Endocrinology and Metabolism University
of Texas Southwestern Medical School, Dallas
Hemal H. Patel, PhD Associate Professor of Anesthesiology
University of California, San Diego Dean, School of Medicine and
Senior Vice President of Health Sciences SUNY Stony Brook, New
York
Piyush M. Patel, MD, FRCPC Professor of Anesthesiology University
of California, San Diego
Trevor M. Penning, PhD Professor of Pharmacology Director, Center
of Excellence in Environmental Toxicology School of Medicine
University of Pennsylvania, Philadelphia
William A. Petri, Jr, MD, PhD Professor of Medicine; Chief,
Division of Infectious Diseases
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Professor of Medicine; Chief, Division of Infectious Diseases
University of Virginia, Charlottesville
Margaret A. Phillips, PhD Professor of Pharmacology University of
Texas Southwestern Medical School, Dallas
Alvin C. Powers, MD Professor of Medicine, Molecular Physiology and
Biophysics Vanderbilt University Medical Center Nashville,
Tennessee
Christopher Rapuano, MD Director, Cornea Service and Refractive
Surgery Department, Wills Eye Institute Philadelphia,
Pennsylvania
Robert F. Reilly, Jr, MD Professor of Internal Medicine University
of Texas Southwestern Medical School, Dallas Chief of Nephrology
VA-North Texas Health Care System, Dallas
Mary V. Relling, PharmD Chair of Pharmaceutical Sciences St. Jude
Childrens' Research Hospital Memphis, Tennessee
Paul G. Richardson, MD Associate Professor of Medicine, Harvard
Medical School Clinical Director, Lipper Center for Multiple
Myeloma Dana-Farber Cancer Institute Boston, Massachusetts
Suzanne M. Rivera, PhD, MSW Assistant Professor of Clinical
Sciences University of Texas Southwestern Medical Center,
Dallas
Erik Roberson, MD, PhD Assistant Professor of Neurology and
Neurobiology University of Alabama, Birmingham
Thomas P. Rocco, MD Associate Professor of Medicine Harvard Medical
School VA-Boston Healthcare System Boston, Massachusetts
David M. Roth, MD, PhD Professor of Anesthesiology University of
California, San Diego VA-San Diego Healthcare System
David P. Ryan, MD Associate Professor of Medicine Harvard Medical
School Massachusetts General Hospital Cancer Center, Boston
Kevin J. Sampson, PhD Postdoctoral Research Scientist in
Pharmacology Columbia University, New York
Elaine Sanders-Bush, PhD Professor (Emerita) of Pharmacology School
of Medicine, Vanderbilt University Nashville, Tennessee
Bernard P. Schimmer, PhD Professor (Emeritus) of Medical Research
and Pharmacology University of Toronto, Ontario
Marc A. Schuckit, MD Distinguished Professor of Psychiatry
University of California, San Diego Director, Alcohol Research
Center VA-San Diego Healthcare System
Lecia Sequist, MD, MPH Assistant Professor of Medicine Harvard
Medical School, Massachusetts General Hospital Cancer Center,
Boston
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Keith A. Sharkey, PhD Professor of Physiology & Pharmacology
and Medicine University of Calgary, Alberta
Richard C. Shelton, MD Professor of Psychiatry and Pharmacology
School of Medicine, Vanderbilt University Nashville,
Tennessee
Danny Shen, PhD Professor and Chair of Pharmacy Professor of
Pharmaceutics, School of Pharmacy University of Washington,
Seattle
Randal A. Skidgel, PhD Professor of Pharmacology and Anesthesiology
College of Medicine, University of Illinois-Chicago
Matthew R. Smith, MD, PhD Associate Professor of Medicine, Harvard
Medical School Physician, Massachusetts General Hospital,
Boston
Emer M. Smyth, PhD Research Assistant, Professor of Pharmacology
University of Pennsylvania, Philadelphia
Peter J. Snyder, MD Professor of Medicine University of
Pennsylvania, Philadelphia
David Standaert, MD, PhD Professor of Neurology Director, Center
for Neurodegeneration and Experimental Therapeutics University of
Alabama, Birmingham
Samuel L. Stanley, Jr, MD Professor of Medicine and President SUNY
Stony Brook, New York
Yuichi Sugiyama, PhD Professor and Chair of Molecular
Pharmacokinetics University of Tokyo, Japan
Jeffrey G. Supko, PhD Associate Professor of Medicine, Harvard
Medical School Massachusetts General Hospital, Boston
Palmer W. Taylor, PhD Professor of Pharmacology, School of Medicine
Dean, Skaggs School of Pharmacy and Pharmaceutical Sciences
University of California, San Diego
Kenneth E. Thummel, PhD Professor and Chair, Department of
Pharmaceutics University of Washington, Seattle
Robert H. Tukey, PhD Professor of Pharmacology and
Chemistry/Biochemistry University of California, San Diego
Flavio Vincenti, MD Professor of Clinical Medicine Medical
Director, Pancreas Transplant Program University of California, San
Francisco
Joseph M. Vinetz, MD Professor of Medicine, Division of Infectious
Diseases University of California, San Diego
Mark S. Wallace, MD Professor of Clinical Anesthesiology University
of California, San Diego
John L. Wallace, PhD, MBA, FRSC Professor and Director, Farncombe
Family Digestive Health Research Institute McMaster University,
Hamilton, Ontario
Jeffrey I. Weitz, MD, FRCP(C), FACP Professor of Medicine,
Biochemistry and Biomedical Sciences McMaster University Executive
Director, Thrombosis & Atherosclerosis
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
12e [Vishal] Contributors
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Executive Director, Thrombosis & Atherosclerosis Research
Institute, Hamilton, Ontario
David P. Westfall, PhD Professor (Emeritus) of Pharmacology
University of Nevada School of Medicine, Reno
Thomas C. Westfall, PhD Professor and Chair of Pharmacological and
Physiological Science St. Louis University School of Medicine,
Missouri
Wyndham Wilson, MD, PhD Senior Investigator and Chief of Lymphoid
Therapeutics Section Center for Cancer Research, National Cancer
Institute Bethesda Maryland
Tony L. Yaksh, PhD Professor of Anesthesiology and Pharmacology
University of California, San Diego
Alexander C. Zambon, PhD Assistant Professor of Pharmacology
University of California, San Diego
Contributors (online)
Donald K. Blumenthal Nelda Murri Randa Hilal-Dandan Lecturer in
Pharmacology University of California, San Diego
Consulting Editor
12 / 2136
Section I. General Principles Chapter 1 Drug Invention & the
Pharmaceutical Industry Chapter 2 Pharmacokinetics: The Dynamics of
Drug Absorption, Distribution, Metabolism &
Elimination Chapter 3 Pharmacodynamics: Molecular Mechanisms of
Drug Action Chapter 4 Drug Toxicity & Poisoning Chapter 5
Membrane Transporters & Drug Response Chapter 6 Drug Metabolism
Chapter 7 Pharmacogenetics
Section II. Neuropharmacology Chapter 8 Neurotransmission: The
Autonomic & Somatic Motor Nervous Systems Chapter 9 Muscarinic
Receptor Agonists & Antagonists Chapter 10 Anticholinesterase
Agents Chapter 11 Agents Acting at the Neuromuscular Junction &
Autonomic Ganglia Chapter 12 Adrenergic Agonists & Antagonists
Chapter 13 5-Hydroxytryptamine (Serotonin) & Dopamine Chapter
14 Neurotransmission & the Central Nervous System Chapter 15
Drug Therapy of Depression & Anxiety Disorders Chapter 16
Pharmacotherapy of Psychosis & Mania Chapter 17 Hypnotics &
Sedatives Chapter 18 Opioids, Analgesia & Pain Management
Chapter 19 General Anesthetics & Therapeutic Gases Chapter 20
Local Anesthetics Chapter 21 Pharmacotherapy of the Epilepsies
Chapter 22 Treatment of Central Nervous System Degenerative
Disorders Chapter 23 Ethanol & Methanol Chapter 24 Drug
Addiction
Section III. Modulation of Cardiovascular Function Chapter 25
Regulation of Renal Function & Vascular Volume Chapter 26 Renin
& Angiotensin Chapter 27 Treatment of Myocardial Ischemia &
Hypertension Chapter 28 Pharmacotherapy of Congestive Heart Failure
Chapter 29 Anti-Arrhythmic Drugs Chapter 30 Blood Coagulation &
Anticoagulant, Fibrinolytic & Antiplatelet Drugs Chapter 31
Drug Therapy for Hypercholesterolemia & Dyslipidemia
Section IV. Inflammation, Immunomodulation & Hematopoiesis
Chapter 32 Histamine, Bradykinin & Their Antagonists Chapter 33
Lipid-Derived Autacoids: Eicosanoids & Platelet-Activating
Factor Chapter 34 Anti-inflammatory, Antipyretic & Analgesic
Agents; Pharmacotherapy of Gout Chapter 35 Immunosuppressants,
Tolerogens & Immunostimulants Chapter 36 Pulmonary Pharmacology
Chapter 37 Hematopoietic Agents: Growth Factors, Minerals &
Vitamins
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Section V. Hormones & Hormone Antagonists Chapter 38
Introduction To Endocrinology: The Hypothalamic-Pituitary Axis
Chapter 39 Thyroid & Anti-Thyroid Drugs Chapter 40 Estrogens
& Progestins Chapter 41 Androgens Chapter 42 ACTH, Adrenal
Steroids & Pharmacology of the Adrenal Cortex Chapter 43
Endocrine Pancreas & Pharmacotherapy of Diabetes Mellitus &
Hypoglycemia Chapter 44 Agents Affecting Mineral Ion Homeostasis
& Bone Turnover
Section VI. Drugs Affecting Gastrointestinal Function Chapter 45
Pharmacotherapy of Gastric Acidity, Peptic Ulcers &
Gastroesophageal Reflux
Disease Chapter 46 Treatment of Disorders of Bowel Motility &
Water Flux; Anti-Emetics; Agents Used in
Biliary & Pancreatic Disease Chapter 47 Pharmacotherapy of
Inflammatory Bowel Disease
Section VII. Chemotherapy of Microbial Diseases Chapter 48 General
Principles of Antimicrobial Therapy Chapter 49 Chemotherapy of
Malaria Chapter 50 Chemotherapy of Protozoal Infections: Amebiasis,
Giardiasis, Trichomoniasis,
Trypanosomiasis, Leishmaniasis & Other Protozoal Infections
Chapter 51 Chemotherapy of Helminth Infections Chapter 52
Sulfonamides, Trimethoprim-Sulfamethoxazole, Quinolones &
Agents for
UrinaryTract Infections Chapter 53 Penicillins, Cephalosporins
& Other β-Lactam Antibiotics Chapter 54 Aminoglycosides Chapter
55 Protein Synthesis Inhibitorsand Miscellaneous Antibacterial
Agents Chapter 56 Chemotherapy of Tuberculosis, Mycobacterium Avium
Complex Disease & Leprosy Chapter 57 Antifungal Agents Chapter
58 Antiviral Agents (Nonretroviral) Chapter 59 Antiretroviral
Agents & Treatment of HIV Infection
Section VIII. Chemotherapy of Neoplastic Diseases Chapter 60
General Principles of Cancer Chemotherapy Chapter 61 Cytotoxic
Agents Chapter 62 Targeted Therapies: Tyrosine Kinase Inhibitors,
Monoclonal Antibodies & Cytokines Chapter 63 Natural Products
in Cancer Chemotherapy: Hormones & Related Agents
Section IX. Special Systems Pharmacology Chapter 64 Ocular
Pharmacology Chapter 65 Dermatological Pharmacology Chapter 66
Contraception & Pharmacotherapy of Obstetrical &
Gynecological Disorders Chapter 67 Environmental Toxicology:
Carcinogens & Heavy Metals
Section X. Appendices
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Goodman & Gilman's The Pharmacological Basis of Therapeutics
> Section I. General Principles > Chapter 1. Drug Invention
and the Pharmaceutical Industry >
DRUG INVENTION AND THE PHARMACEUTICAL INDUSTRY: INTRODUCTION The
first edition of this textbook, published in 1941, is often
credited with organizing the field of pharmacology, giving it
intellectual validity and an academic identity. That first edition
began: "The subject of pharmacology is a broad one and embraces the
knowledge of the source, physical and chemical properties,
compounding, physiological actions, absorption, fate, and
excretion, and therapeutic uses of drugs. A drug may be broadly
defined as any chemical agent that affects living protoplasm, and
few substances would escape inclusion by this definition." These
two sentences still serve us well. This first section of the 12th
edition of this textbook provides the underpinnings for these
definitions by exploring the processes of drug invention and
development into a therapeutic entity, followed by the basic
properties of the interactions between the drug and biological
systems: pharmacodynamics, pharmacokinetics (including drug
transport and metabolism), and pharmacogenomics. Subsequent
sections deal with the use of drugs as therapeutic agents in human
subjects. We intentionally use the term invention to describe the
process by which a new drug is identified and brought to medical
practice, rather than the more conventional term discovery. This
significant semantic change was suggested to us by our colleague
Michael S. Brown, MD, and it is appropriate. In the past, drugs
were discovered as natural products and used as such. Today, useful
drugs are rarely discovered hiding somewhere waiting to be found;
rather, they are sculpted and brought into being based on
experimentation and optimization of many independent properties.
The term invention emphasizes this process; there is little
serendipity. *Alfred G. Gilman serves on the Board of Directors of
Eli Lilly & Co. and Regeneron Pharmaceuticals, and acknowledges
potential conflicts of interests. FROM EARLY EXPERIENCES WITH
PLANTS TO MODERN CHEMISTRY Man's fascination—and sometimes
infatuation—with chemicals (i.e., drugs) that alter biological
function is ancient and arose as a result of experience with and
dependence on plants. Most plants are root-bound, and many have
become capable of elaborate chemical syntheses, producing harmful
compounds for defense that animals learned to avoid and man learned
to exploit. Many examples are described in earlier editions of this
text: the appreciation of coffee (caffeine) by the prior of an
Arabian convent who noted the behavior of goats that gamboled and
frisked through the night after eating the berries of the coffee
plant, the use of mushrooms or the deadly nightshade plant
(containing the belladonna alkaloids atropine and scopolamine) by
professional poisoners, and a rather different use of belladonna
("beautiful lady") to dilate pupils. Other examples include the
uses of the Chinese herb ma huang (containing ephedrine) for over
5000 years as a circulatory stimulant, curare-containing arrow
poisons used for centuries by South American Indians to paralyze
and kill animals hunted for food, and poppy juice (opium)
containing morphine (from the Greek Morpheus, the god of dreams)
for pain relief and control of dysenteries. Morphine, of course,
has well-known addicting properties, mimicked in some ways by other
problematic ("recreational") natural products—nicotine, cocaine,
and ethanol. While many terrestrial and marine organisms remain
valuable sources of naturally occurring compounds with various
pharmacological activities, especially including lethal effects on
both microorganisms and eukaryotic cells, drug invention became
more allied with synthetic organic chemistry as that discipline
flourished over the past 150 years. This revolution began in the
dye industry. Dyes, by definition, are colored compounds with
selective affinity for biological tissues. Study of these
interactions stimulated Paul Ehrlich to postulate the existence of
chemical receptors in tissues that interacted with and "fixed" the
dyes. Similarly, Ehrlich thought that unique receptors on
microorganisms or parasites might react specifically with certain
dyes and that such selectivity could spare normal tissue. Ehrlich's
work culminated in the invention of arsphenamine in 1907, which was
patented as "salvarsan," suggestive of the hope that the chemical
would be the salvation of humankind. This arsenic-containing
compound and other organic arsenicals were invaluable for the
chemotherapy of syphilis until the discovery of penicillin. During
that period and thanks to the work of Gerhard Domagk, another dye,
prontosil (the first clinically useful sulfonamide) was shown to be
dramatically effective in treating streptococcal infections. The
era of antimicrobial chemotherapy was born, and the fascination
with dyes soon spread to the entire and nearly infinite spectrum of
organic chemicals. The resulting collaboration of pharmacology with
chemistry on the one hand, and with clinical medicine on the other,
has been a major contributor to the effective treatment
Goodman & Gilman's The Pharmacological Basis of Therapeutics,
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of disease, especially since the middle of the 20th century.
SOURCES OF DRUGS Small Molecules Are the Tradition With the
exception of a few naturally occurring hormones such as insulin,
most drugs were small organic molecules (typically <500 Da)
until recombinant DNA technology permitted synthesis of proteins by
various organisms (bacteria, yeast) and mammalian cells, starting
in the 1980s. The usual approach to invention of a small-molecule
drug is to screen a collection of chemicals ("library") for
compounds with the desired features. An alternative is to
synthesize and focus on close chemical relatives of a substance
known to participate in a biological reaction of interest (e.g.,
congeners of a specific enzyme substrate chosen to be possible
inhibitors of the enzymatic reaction), a particularly important
strategy in the discovery of anticancer drugs. While drug discovery
in the past often resulted from serendipitous observations of the
effects of plant extracts or individual chemicals administered to
animals or ingested by man, the approach today relies on
high-throughput screening of libraries containing hundreds of
thousands or even millions of compounds for their ability to
interact with a specific molecular target or elicit a specific
biological response (see "Targets of Drug Action" later in the
chapter). Chemical libraries are synthesized using modern organic
chemical synthetic approaches such as combinatorial chemistry to
create large collections of related chemicals, which can then be
screened for activity in high-throughput systems.
Diversity-oriented synthetic approaches also are of obvious value,
while natural products (plant or marine animal collections) are
sources of novel and sometimes exceedingly complex chemical
structures. Automated screening procedures employing robotic
systems can process hundreds of thousands of samples in just a few
days. Reactions are carried out in small trays containing a matrix
of tiny wells (typically 384 or 1536). Assay reagents and samples
to be tested are coated onto plates or distributed by robots, using
ink-jet technology. Tiny volumes are used and chemical samples are
thus conserved. The assay must be sensitive, specific, and designed
to yield a readily detectable signal, usually a change in
absorption or emission of light (fluorescence, luminescence,
phosphorescence) or alteration of a radioactive substrate. The
signal may result from the interaction of a candidate chemical with
a specific protein target, such as an enzyme or a biological
receptor protein that one hopes to inhibit or activate with a drug.
Alternatively, cell-based high-throughput screens may be performed.
For example, a cell may be engineered to emit a fluorescent signal
when Ca2+ fluxes into the cell as a result of a ligand-receptor
interaction. Cellular engineering is accomplished by transfecting
the necessary genes into the cell, enabling it to perform the
functions of interest. It is of enormous value that the specific
protein target in an assay or the molecules used to engineer a cell
for a high-throughput screen are of human origin, obtained by
transcription and translation of the cloned human gene. The
potential drugs that are identified in the screen ("hits") are thus
known to react with the human protein and not just with its
relative (ortholog) obtained from mouse or another species. Several
variables affect the frequency of hits obtained in a screen. Among
the most important are the "drugability" of the target and the
stringency of the screen in terms of the concentrations of
compounds that are tested. The slang term "drugability" refers to
the ease with which the function of a target can be altered in the
desired fashion by a small organic molecule. If the protein target
has a well-defined binding site for a small molecule (e.g., a
catalytic or allosteric site), chances are excellent that hits will
be obtained. If the goal is to employ a small molecule to mimic or
disrupt the interaction between two proteins, the challenge is much
greater. From Hits to Leads Only rarely do any of the initial hits
in a screen turn out to be marketable drugs. Initial hits often
have modest affinity for the target, and lack the desired
specificity and pharmacological properties of a successful
pharmaceutical. Skilled medicinal chemists synthesize derivatives
of the hits, making substitutions at accessible positions, and
begin in this way to define the relationship between chemical
structure and biological activity. Many parameters may require
optimization, including affinity for the target, agonist/antagonist
activity, permeability across cell membranes, absorption and
distribution in the body, metabolism of the drug, and unwanted
effects. While this approach was driven largely by instinct and
trial and error in the past, modern drug development frequently
takes advantage of determination of a high- resolution structure of
the putative drug bound to its target. X-ray crystallography offers
the most detailed structural information if the target protein can
be crystallized with the lead drug bound to it. Using techniques of
molecular modeling and computational chemistry, the structure
provides the chemist with
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information about substitutions likely to improve the "fit" of the
drug with the target and thus enhance the affinity of the drug for
its target (and, hopefully, optimize selectivity of the drug
simultaneously). Nuclear magnetic resonance (NMR) spectroscopy is
another valuable technique for learning the structure of a
drug-receptor complex. NMR studies are done in solution, with the
advantage that the complex need not be crystallized. However, the
structures obtained by NMR spectroscopy usually are not as precise
as those from X-ray crystallography, and the protein target must
not be larger than roughly 35–40 kDa. The holy grail of this
approach to drug invention will be to achieve success entirely
through computation. Imagine a database containing detailed
chemical information about millions of chemicals and a second
database containing detailed structural information about all human
proteins. The computational approach is to "roll" all the chemicals
over the protein of interest to find those with high-affinity
interactions. The dream gets bolder if we acquire the ability to
roll the chemicals that bind to the target of interest over all
other human proteins to discard compounds that have unwanted
interactions. Finally, we also will want to predict the structural
and functional consequences of a drug binding to its target (a huge
challenge), as well as all relevant pharmacokinetic properties of
the molecules of interest. We are a long way from realization of
this fabulous dream; however, we are sufficiently advanced to
imagine it and realize that it could someday be a reality. Indeed,
computational approaches have suggested new uses for old drugs and
offered explanations for recent failures of drugs in the later
stages of clinical development (e.g., torcetrapib; see below) (Kim
et al., 2010; Kinnings et al., 2009; Xie et al., 2007, 2009). Large
Molecules Are Increasingly Important Protein therapeutics were
uncommon before the advent of recombinant DNA technology. Insulin
was introduced into clinical medicine for the treatment of diabetes
following the experiments of Banting and Best in 1921. Insulin
could be produced in great quantities by purification from porcine
or bovine pancreas obtained from slaughter houses. These insulins
are active in man, although antibodies to the foreign proteins are
occasionally problematic. Growth hormone, used to treat pituitary
dwarfism, is a case of more stringent species specificity: only the
human hormone could be used after purification from pituitary
glands harvested during autopsy. The danger of this approach was
highlighted when patients who had received the human hormone
developed Creutzfeldt-Jakob disease (the human equivalent of mad
cow disease), a fatal degenerative neurological disease caused by
prion proteins that contaminated the drug preparation. Thanks to
gene cloning and the ability to produce large quantities of
proteins by expressing the cloned gene in bacteria or eukaryotic
cells grown in enormous (30,000-liter) bioreactors, protein
therapeutics now utilize highly purified preparations of human (or
humanized) proteins. Rare proteins can now be produced in quantity,
and immunological reactions are minimized. Proteins can be
designed, customized, and optimized using genetic engineering
techniques. Other types of macromolecules may also be used
therapeutically. For example, antisense oligonucleotides are used
to block gene transcription or translation, as are small
interfering RNAs (siRNAs). Proteins utilized therapeutically
include various hormones, growth factors (e.g., erythropoietin,
granulocyte-colony stimulating factor), and cytokines, as well as a
rapidly increasing number of monoclonal antibodies now widely used
in the treatment of cancer and autoimmune diseases. Murine
monoclonal antibodies can be "humanized" (by substituting human for
mouse amino acid sequences). Alternatively, mice have now been
"engineered" by replacement of critical mouse genes with their
human equivalents, such that they make completely human antibodies.
Protein therapeutics are administered parenterally, and their
receptors or targets must be accessible extracellularly. TARGETS OF
DRUG ACTION The earliest drugs came from observation of the effects
of plants after their ingestion by animals. One could observe at
least some of the effects of the chemical(s) in the plant and, as a
side benefit, know that the plant extract was active when taken
orally. Valuable drugs were discovered with no knowledge of their
mechanism or site of action. While this approach is still useful
(e.g., in screening for the ability of natural products to kill
microorganisms or malignant cells), modern drug invention usually
takes the opposite approach—starting with a statement (or
hypothesis) that a certain protein or pathway plays a critical role
in the pathogenesis of a certain disease, and that altering the
protein's activity would therefore be effective against that
disease. Crucial questions arise:
can one find a drug that will have the desired effect against its
target? does modulation of the target protein affect the course of
disease? does this project make sense economically?
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The effort that may be expended to find the desired drug will be
determined by the degree of confidence in the answers to the latter
two questions. Is the Target "Drugable"? The drugability of a
target with a low-molecular-weight organic molecule relies on the
presence of a binding site for the drug that can be approached with
considerable affinity and selectivity. If the target is an enzyme
or a receptor for a small ligand, one is encouraged. If the target
is related to another protein that is known to have, for example, a
binding site for a regulatory ligand, one is hopeful. However, if
the known ligands are large peptides or proteins with an extensive
set of contacts with their receptor, the challenge is much greater.
If the goal is to disrupt interactions between two proteins, it may
be necessary to find a "hot spot" that is crucial for the
protein-protein interaction, and such a region may not be detected.
Accessibility of the drug to its target also is critical.
Extracellular targets are intrinsically easier to approach and, in
general, only extracellular targets are accessible to
macromolecular drugs. Has the Target Been Validated? This question
is obviously a critical one. A negative answer, frequently obtained
only retrospectively, is a common cause of failure in drug
invention. Based on extensive study of a given biological process,
one may believe that protein X plays a critical role in
pathological alterations of that process. However, biological
systems frequently contain redundant elements, and they are
adaptable. When the activity of protein X is, e.g., inhibited by a
drug, redundancy in the system may permit compensation. The system
also may adapt to the presence of the drug, perhaps by regulating
the expression of the target or of functionally related gene
products. In general, the more important the function, the greater
the complexity of the system. For example, many mechanisms control
feeding and appetite, and drugs to control obesity have been
notoriously difficult to find. The discovery of the hormone leptin,
which suppresses appetite, was based on mutations in mice that
cause loss of either leptin or its receptor; either kind of
mutation results in enormous obesity in both mice and people.
Leptin thus appeared to be a marvelous opportunity to treat
obesity. However, obese individuals have high circulating
concentrations of leptin and appear quite insensitive to its
action. Modern techniques of molecular biology offer new and
powerful tools for validation of potential drug targets, to the
extent that the biology of model systems resembles human biology.
Genes can be inserted, disrupted, and altered in mice. One can
thereby create models of disease in animals or mimic the effects of
long-term disruption or activation of a given biological process.
If, for example, disruption of the gene encoding a specific enzyme
or receptor has a beneficial effect in a valid murine model of a
human disease, one may believe that the potential drug target has
been validated. Mutations in humans also can provide
extraordinarily valuable information. For example, loss-of-function
mutations in the PCSK9 gene (encoding proprotein convertase
subtilisin/kexin type 9) greatly lower concentrations of LDL
cholesterol in plasma and reduce the risk of myocardial infarction
(Horton et al., 2009). This single powerful observation speaks to a
well-validated drug target. Based on these findings, many drug
companies are actively seeking inhibitors of PCSK9 function. Is
This Drug Invention Effort Economically Viable? Drug invention and
development is extraordinarily expensive, as discussed later in the
chapter. Economic realities influence the direction of science. For
example, investor-owned companies generally cannot afford to
develop products for rare diseases or for diseases that are common
only in economically underdeveloped parts of the world. Funds to
invent drugs targeting rare diseases or diseases primarily
affecting developing countries (especially parasitic diseases) can
come from taxpayers or very wealthy philanthropists; such funds
generally will not come from private investors involved in running
for-profit companies. ADDITIONAL PRECLINICAL RESEARCH Following the
path just described can yield a potential drug molecule that
interacts with a validated target and alters its function in the
desired fashion (either enhancing or inhibiting the functions of
the target). Now one must consider all aspects of the molecule in
question—its affinity and selectivity for interaction with the
target, its pharmacokinetic properties (absorption, distribution,
excretion, metabolism), issues with regard to its large-scale
synthesis or purification from a natural source, its pharmaceutical
properties (stability, solubility, questions of formulation), and
its safety. One hopes to correct, to the extent possible, any
obvious deficiencies by modification of the molecule itself or by
changes in the way the molecule is presented for use. Before being
administered to people, potential drugs are tested for general
toxicity by monitoring the
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activity of various systems in two species of animals for extended
periods of time. Compounds also are evaluated for carcinogenicity,
genotoxicity, and reproductive toxicity. Animals are used for much
of this testing, although the predictive value of results obtained
in nonhuman species is certainly not perfect. Usually one rodent
(usually mouse) and one non-rodent (often rabbit) species are used.
In vitro and ex vivo assays are utilized when possible, both to
spare animals and to minimize cost. If an unwanted effect is
observed, an obvious question is whether it is mechanism-based
(i.e., caused by interaction of the drug with its intended target)
or due to an off-target effect of the drug. If the latter, there is
hope of minimizing the effect by further optimization of the
molecule. Before clinical trials of a potential new drug may
proceed in the U.S. (that is, before the drug candidate can be
administered to a human subject), the sponsor must file an IND
(Investigational New Drug) application, which is a request to the
U.S. Food and Drug Administration (FDA; see the next section) for
permission to administer the drug to human test subjects. The IND
describes the rationale and preliminary evidence for efficacy in
experimental systems, as well as pharmacology, toxicology,
chemistry, manufacturing, and so forth. It also describes the plan
for investigating the drug in human subjects. The FDA has 30 days
to review the application, by which time the agency may disapprove
the application, ask for more data, or allow initial clinical
testing to proceed. In the absence of an objection or request for
more information within 30 days by the FDA, a clinical trial may
begin. CLINICAL TRIALS AND THE ROLE OF THE FDA The FDA is a
regulatory agency within the U.S. Department of Health and Human
Services. As its mission statement indicates, the FDA:
is responsible for protecting the public health by assuring the
safety, efficacy, and security of human and veterinary drugs,
biological products, medical devices, our nation's food supply,
cosmetics, and products that emit radiation. The FDA is also
responsible for advancing the public health by helping to speed
innovations that make medicines and foods more effective, safer,
and more affordable; and helping the public get the accurate,
science-based information they need to use medicines and foods to
improve their health (FDA, 2009).
The first drug-related legislation in the U.S., the Federal Food
and Drug Act of 1906, was concerned only with the interstate
transport of adulterated or misbranded foods and drugs. There were
no obligations to establish drug efficacy or safety. This act was
amended in 1938, after the deaths of 105 children from "elixir
sulfanilamide," a solution of sulfanilamide in diethylene glycol,
an excellent but highly toxic solvent and an ingredient in
antifreeze. The enforcement of the amended act was entrusted to the
FDA. Toxicity studies as well as approval of a New Drug Application
(NDA; see the next section) were required before a drug could be
promoted and distributed. Although a new drug's safety had to be
demonstrated, no proof of efficacy was required. In the 1960s,
thalidomide, a hypnotic drug with no obvious advantages over
others, was introduced in Europe. Epidemiological research
eventually established that this drug, taken early in pregnancy,
was responsible for an epidemic of a relatively rare and severe
birth defect, phocomelia. In reaction to this catastrophe, the U.S.
Congress passed the Harris-Kefauver amendments to the Food, Drug,
and Cosmetic Act in 1962. These amendments established the
requirement for proof of efficacy as well of documentation of
relative safety in terms of the risk-to-benefit ratio for the
disease entity to be treated (the more serious the disease, the
greater the acceptable risk).
One of the agency's primary responsibilities is to protect the
public from harmful medications. However, the FDA clearly faces an
enormous challenge, especially in view of the widely held belief
that its mission cannot possibly be accomplished with the available
resources. Moreover, harm from drugs that cause unanticipated
adverse effects is not the only risk of an imperfect system; harm
also occurs when the approval process delays the marketing of a new
drug with important beneficial effects. Determining safety and
efficacy prior to mass marketing requires careful consideration.
The Conduct of Clinical Trials Clinical trials (as applied to
drugs) are investigations in human subjects intended to acquire
information about the pharmacokinetic and pharmacodynamic
properties of a potential drug. Depending on the nature and phase
of the trial, it may be designed to evaluate a drug's safety, its
efficacy for treatment or prevention of specific conditions in
patients, and its tolerability and side effects. Efficacy must be
proven and an adequate margin of safety established for a drug to
be approved for sale in the U.S. The U.S. National Institutes of
Health notes seven ethical requirements that must be met before a
clinical trial can begin. These include social value, scientific
validity, fair and objective selection of subjects, informed
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consent, favorable ratio of risks to benefits, approval and
oversight by an independent review board (IRB), and respect for
human subjects. FDA-regulated clinical trials typically are
conducted in four phases. The first three are designed to establish
safety and efficacy, while Phase IV post-marketing trials delineate
additional information regarding new indications, risks, and
optimal doses and schedules. Table 1–1 and Figure 1–1 summarize the
important features of each phase of clinical trials, especially the
attrition at each successive stage over a relatively long and
costly process.
Table 1–1 Typical Characteristics of the Various Phases of the
Clinical Trials Required for Marketing of New Drugs.
PHASE I First in Human
PHASE II First in Patient
PHASE III Multi-Site Trial
PHASE IV Post-Marketing Surveillance
10-100 participants 50-500 participants A few hundred to a few
thousand participants
Many thousands of participants
Usually healthy volunteers; occasionally patients with advanced or
rare disease
Patient-subjects receiving experimental drug
Patient-subjects receiving experimental drug
Patients in treatment with approved drug
Open label Randomized and controlled (can be placebo-controlled);
may be blinded
Randomized and controlled (can be placebo-controlled) or
uncontrolled; may be blinded
Open label
Confirm efficacy in larger population
Adverse events, compliance, drug- drug interactions
Months to 1 year 1-2 years 3-5 years No fixed duration U.S. $10
million US $20 million US $50-100 million — Success rate: 50%
Success rate: 30% Success rate: 25-50% —
Figure 1–1.
The phases, time lines, and attrition that characterize the
invention of new drugs. See also Table 1–1.
When initial Phase III trials are complete, the sponsor (usually a
pharmaceutical company) applies to the FDA for approval to market
the drug; this application is called either a New Drug Application
(NDA) or a Biologics License Application (BLA). These applications
contain comprehensive information, including individual case-report
forms from the hundreds or thousands of individuals who have
received the drug
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during its Phase III testing. Applications are reviewed by teams of
specialists, and the FDA may call on the help of panels of external
experts in complex cases. The use of such external advisory
committees greatly expands the talent pool available to assist in
making important and difficult decisions. Under the provisions of
the Prescription Drug User Fee Act (PDUFA, enacted initially in
1992 and renewed in 2007), pharmaceutical companies now provide a
significant portion of the FDA budget via user fees, a legislative
effort to expedite the drug approval review process. PDUFA also
broadened the FDA's drug safety program and increased resources for
review of television drug advertising. The larger FDA staffing now
in place has shortened the time required for review; nevertheless,
the process is a lengthy one. A1-year review time is considered
standard, and 6 months is the target if the drug candidate is
granted priority status because of its importance in filling an
unmet need. Unfortunately, these targets are not always met. Before
a drug is approved for marketing, the company and the FDA must
agree on the content of the "label" (package insert)—the official
prescribing information. This label describes the approved
indications for use of the drug and clinical pharmacological
information including dosage, adverse reactions, and special
warnings and precautions (sometimes posted in a "black box").
Promotional materials used by pharmaceutical companies cannot
deviate from information contained in the package insert.
Importantly, the physician is not bound by the package insert; a
physician in the U.S. may legally prescribe a drug for any purpose
that she or he deems reasonable. However, third-party payers
(insurance companies, Medicare, and so on) generally will not
reimburse a patient for the cost of a drug used for an "off-label"
indication unless the new use is supported by one of several
compendia such as the U.S. Pharmacopeia. Furthermore, a physician
may be vulnerable to litigation if untoward effects result from an
unapproved use of a drug. Determining "Safe" and "Effective" To
demonstrate efficacy to the FDA requires performing "adequate and
well-controlled investigations," generally interpreted to mean two
replicate clinical trials that are usually, but not always,
randomized, double-blind, and placebo-controlled. Is a placebo the
proper control? The World Medical Association's Declaration of
Helsinki (2000) discourages use of placebo controls when an
alternative treatment is available for comparison. What must be
measured in the trials? In a straightforward trial, a readily
quantifiable parameter (a secondary or surrogate end point),
thought to be predictive of relevant clinical outcomes, is measured
in matched drug- and placebo-treated groups. Examples of surrogate
end points include LDL cholesterol as a predictor of myocardial
infarction, bone mineral density as a predictor of fractures, or
hemoglobin A1c as a predictor of the complications of diabetes
mellitus. More stringent trials would require demonstration of
reduction of the incidence of myocardial infarction in patients
taking a candidate drug in comparison with those taking an HMG-CoA
reductase inhibitor (statin) or other LDL cholesterol-lowering
agent, or reduction in the incidence of fractures in comparison
with those taking a bisphosphonate. Use of surrogate end points
significantly reduces cost and time required to complete trials but
there are many mitigating factors, including the significance of
the surrogate end point to the disease or condition that the
candidate drug is intended to treat.
Some of the difficulties are well illustrated by recent experiences
with ezetimibe, a drug that inhibits absorption of cholesterol from
the gastrointestinal tract and lowers LDL cholesterol
concentrations in plasma, especially when used in combination with
a statin. Lowering of LDL cholesterol was assumed to be an
appropriate surrogate end point for the effectiveness of ezetimibe
to reduce myocardial infarction and stroke, consequences of
cholesterol accumulation in foam cells beneath the endothelium of
vessels. Surprisingly, the ENHANCE trial demonstrated that the
combination of ezetimibe and a statin did not reduce intima-media
thickness of carotid arteries (a more direct measure of
sub-endothelial cholesterol accumulation) compared with the statin
alone, despite the fact that the drug combination lowered LDL
cholesterol concentrations substantially more than did either drug
alone (Kastelein et al., 2008). Critics of ENHANCE argue that the
patients in the study had familial hypercholesterolemia, had been
treated with statins for years, and did not have carotid artery
thickening at the initiation of the study. Should ezetimibe have
been approved? Must we return to measurement of true clinical end
points (e.g., myocardial infarction) before approval of drugs that
lower cholesterol by novel mechanisms? The costs involved in such
extensive and expensive trials must be borne somehow (costs are
discussed later in the chapter). Such a study (IMPROVE-IT) is now
in progress; thousands of patients are enrolled and we will know
the outcome in a few years.
The drug torcetrapib provides a related example in the same
therapeutic area. Torcetrapib elevates
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HDL cholesterol (the "good cholesterol"), and higher levels of HDL
cholesterol are statistically associated with (are a surrogate end
point for) a lower incidence of myocardial infarction.
Surprisingly, clinical administration of torcetrapib caused a
significant increase in mortality from cardiovascular events,
ending a development path of 15 years and $800 million. (For a
recent computational-systems biologic analysis that may explain
this failure, see Xie et al., 2009.) In this case, approval of the
drug based on this secondary end point would have been a mistake
(Cutler, 2007).
The concept of drug safety is perhaps even more complex (Institute
of Medicine, 2007). No drug is totally safe; all drugs produce
unwanted effects in at least some people at some dose. Many
unwanted and serious effects of drugs occur so infrequently,
perhaps only once in several thousand patients, that they go
undetected in the relatively small populations (a few thousand) in
the standard Phase III clinical trial (Table 1–1). To detect and
verify that such events are in fact drug-related would require
administration of the drug to tens or hundreds of thousands of
people during clinical trials, adding enormous expense and time to
drug development and delaying access to potentially beneficial
therapies. In general, the true spectrum and incidence of untoward
effects becomes known only after a drug is released to the broader
market and used by a large number of people (Phase IV,
post-marketing surveillance). Drug development costs, and thus drug
prices, could be reduced substantially if the public were willing
to accept more risk. This would require changing the way we think
about a pharmaceutical company's liability for damages from an
unwanted effect of a drug that was not detected in clinical trials
deemed adequate by the FDA. While the concept is obvious, many lose
sight of the fact that extremely severe unwanted effects of a drug,
including death, may be deemed acceptable if its therapeutic effect
is sufficiently unique and valuable. Such dilemmas can become
issues for great debate. The sufficiency of a therapeutic effect in
the presence of an unwanted effect of a drug may be quite
subjective. One person's meat may indeed be another person's
poison. Great effort may be made to quantify the ratio of risks to
benefits, but the answers are frequently not simple.
Several strategies exist to detect adverse reactions after
marketing of a drug, but debate continues about the most efficient
and effective method. Formal approaches for estimation of the
magnitude of an adverse drug response include the follow-up or
"cohort" study of patients who are receiving a particular drug; the
"case-control" study, where the frequency of drug use in cases of
adverse responses is compared to controls; and meta-analysis of
pre- and post-marketing studies. Because of the shortcomings of
these types of studies to detect what may be a relatively rare
event, additional approaches must be used. Spontaneous reporting of
adverse reactions has proven to be an effective way to generate an
early signal that a drug may be causing an adverse event (Aagard
and Hansen, 2009). It is the only practical way to detect rare
events, events that occur after prolonged use of drug, adverse
effects that are delayed in appearance, and many drug-drug
interactions. Recently, considerable effort has gone into improving
the reporting system in the U.S., called MedWatch (Brewer and
Colditz, 1999; Kessler et al., 1993; see also Appendix 1). Still,
the voluntary reporting system in the U.S. is not nearly as robust
as the legally mandated systems of some other countries. A
disturbing number of physicians are not aware that the FDA has a
reporting system for adverse drug reactions, even though the system
has been repeatedly publicized in major medical journals (Trontell,
2004). Relatively few physicians actually file adverse drug
response reports; those received frequently are incomplete or of
such poor quality that the data are not considered reliable
(Fontarosa et al., 2004).
The most important spontaneous reports are those that describe
serious reactions. Reports on newly marketed drugs (within the
first 5 years of a drug's introduction) are the most significant,
even though the physician may not be able to attribute a causal
role to a particular drug. This system provides early warning
signals of unexpected adverse effects that can then be investigated
by more formal techniques. However, the system also serves to
monitor changes in the nature or frequency of adverse drug
reactions due to aging of the population, changes in the disease
itself, or the introduction of new, concurrent therapies. The
primary sources for the reports are responsible, alert physicians;
other potentially useful sources are nurses, pharmacists, and
students in these disciplines. In addition, hospital-based pharmacy
and therapeutics committees and quality assurance committees
frequently are charged with monitoring adverse drug reactions in
hospitalized patients, and reports from these committees should be
forwarded to the FDA. The simple forms for reporting may be
obtained 24 hours a day, 7 days a week by calling 800-FDA-1088;
alternatively, adverse reactions can be reported directly using the
Internet (www.fda.gov/medwatch). Health professionals
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also may contact the pharmaceutical manufacturer, who is legally
obligated to file reports with the FDA. With this facile reporting
system, the clinician can serve as a vital sentinel in the
detection of unexpected adverse reactions to drugs.
PUBLIC POLICY CONSIDERATIONS AND CRITICISMS OF THE PHARMACEUTICAL
INDUSTRY There is no doubt that drugs can save lives, prolong
lives, and improve the quality of people's lives. Like adequate
nutrition, vaccinations and medications are important for public
health. However, in a free- market economy, access to safe and
effective drugs (or any kind of healthcare, for that matter) is not
equitable. Not surprisingly, there is a substantial tension between
those who would treat drugs as entitlements and those who view
drugs as high-tech products of a capitalistic society. Supporters
of the entitlement position argue that the constitutional right to
life should guarantee access to drugs and other healthcare, and
they are critical of pharmaceutical companies and others who profit
from the business of making and selling drugs. Free-marketers point
out that, without a profit motive, it would be difficult to
generate the resources and innovation required for new drug
development. The media tend to focus on public policy with regard
to the ethics of drug testing, the effectiveness of government
regulations, and conflicts of interest on the part of researchers,
physicians, and others who may have a personal stake in the success
of a drug. In addition, high-profile legal battles have been waged
recently over access to experimental (non-FDA-approved) drugs and
over injuries and deaths resulting from both experimental and
approved drugs. Clearly the public has an interest in both the
pharmaceutical industry and its oversight. Consequently, drug
development is not only a scientific process but also a political
one in which attitudes can change quickly. Little more than a
decade ago Merck was named as America's most admired company by
Fortune magazine seven years in a row—a record that still stands.
Today, Johnson and Johnson is the only pharmaceutical company in
the top 50 of the most- admired list, and this likely reflect their
sales of consumer products, such as band-aids and baby oil, rather
than pharmaceuticals. The next sections explore some of the more
controversial issues surrounding drug invention and development and
consider some of the more strident criticisms that have been
leveled at the pharmaceutical industry (Angell, 2004). Mistrust of
Scientists and Industry Those critical of the pharmaceutical
industry frequently begin from the position that people (and
animals) need to be protected from greedy and unscrupulous
companies and scientists (Kassirer, 2005). They can point to the
very unfortunate (and highly publicized) occurrences of graft,
fraud, and misconduct by scientists and industry executives, and
unethical behavior in university laboratories and community
physicians' offices. These problems notwithstanding, development of
new and better drugs is good for people and animals. In the absence
of a government-controlled drug development enterprise, our current
system relies predominan