INJECTABLE DRUG
`
`DEVELOPMENT
`
`TECHNIQUES TO REDUCE
`PAIN AND IRRITATION
`
`Edited by
`
`Pramod K. Gupta
`
`and
`
`Gayle A. Brazeau
`
`Interpharm Press
`Denver, Colorado
`
` VINTERPHARM‘
`
`P R E S S
`
`Astraleneca Ex. 2087 p. 1
`Mylan Pharms. Inc. V. Astraleneca AB IPR2016-01325
`
`

`
`F.:'.—-""-
`
`E-
`
`Lihrary of Congress Cataloging-in—Publication Data
`
`Injectable drug development : techniques to reduce pain and irritation I
`edited by Prarnod K. Gupta and Gayle A. Brazeau.
`p.
`cm.
`
`Includes bibliographical references and index.
`ISBN ‘1—5?491—095—?
`
`1. Injections. 2. Injections=Complic.ations. 3. Drug development.
`I. Gupta, Prarnod K., 1959-
`. II. Brazeau, Gayle A.
`IDNLM: ‘1. Injections—adverse effects. 2. Pain—chemicaily induced.
`3. Pain—pre-vention 8: control. 4. Pharmaceutical Preparations-—
`administration Si dosage. WB 354 155 1999]
`Rl\/1169.149
`1999
`B1526-—dc2’1
`DNLM/DLC
`
`for Library of Congress
`
`99-26911
`CIP
`
`10987654321
`
`ISBN: 1—57491-095-7
`
`Copyright © 1999 by lnterpharm Press- All rights reserved.
`
`All rights reserved. This book is protected by copyright. No part of it may be re-
`produced, stored in a retrieval system, or transmitted in any form or by any
`means, electronic, mechanical, photocopying, recording, or otherwise, without
`written permission from the publisher. Printed in the United States of America.
`Where a product trademark, registration mark, or other protected mark is
`made in the text, ownership of the mark remains with the lawful owner of the
`mark. No claim, intentional or otherwise, is made by reference to any such marks
`in this book.
`
`While every effort has been made by Interpharm Press to ensure the accuracy
`of the information contained in this book, this organization accepts no responsi-
`bility for errors or omissions.
`
`lnterpharrn Press
`15 Inverness Way E.
`Englewood, CO 80112-5776, USA
`
`Phone: +1-303-662-9101
`Fax:
`+’l—303-754-3953
`Orders/on-line catalog:
`www.interpharrn.corn
`
`Astrazeneca Ex. 2087 p. 2
`
`Invitation to Authors
`
`Interpharrn Press publishes books focused upon applied tech-
`I nology and regulatory affairs impacting healthcare manufactur-
`ers worldwide. If you are considering writing or contributing to
`a book applicable to the pharmaceutical, biotechnology, medical
`device, diagnostic, cosmetic, or veterinary medicine manufacturing in-
`dustries, please Contact our director of publications.
`
`m_
`
`____....
`
`

`
`Contents
`
`Preface
`
`Acknowledgments
`
`Editors and Contributors
`
`A: BACKGROUND OF PAIN, IRRITATION, AND/OR
`MUSCLE DAMAGE WITH INJECTABLES
`
`'1.
`
`Challenges in the Development of
`Injectable Products
`
`Michael J. Akers
`
`General Challenges
`
`Safety Concerns
`
`Microbiological and Other Contamination Challenges
`
`Stability Challenges
`
`Solubility Challenges
`
`Packaging Challenges
`
`Manufacturing Challenges
`
`DeliveryXAdministration Challenges
`
`References
`
`xiii
`
`xiv
`
`xv
`
`3
`
`4
`
`5
`
`6
`
`8
`
`'10
`
`11
`
`11
`
`13
`
`14
`
`iii
`
`Astrazeneca Ex. 2087 p. 3
`
`

`
`iv
`
`lnjectable Drug Development
`
`Pain, Irritation, and Tissue Damage
`with Injections
`
`Wolfgang Klement
`
`Must Injections Hurt?
`
`Mechanisms of Pain and Damage
`
`Routes of Drug Injection
`
`Cutaneous/Subcutaneous Injections
`
`I8
`
`lntramuscularlnjections
`
`22
`
`Intra-aiteriallnjections
`
`24
`
`Intravenous Injections
`
`26
`
`Conclusions and Perspectives
`
`Acknowledgements
`
`References
`
`Mechanisms of Muscle Damage with
`Injectable Products
`
`Anne McArdle and Malcolm J. Jackson
`
`Abstract
`
`Introduction
`
`Mechanisms of Muscle Damage
`
`Elevation oflntracellular Calcium Concentration
`
`58
`
`Increased Free Radical Production
`
`60
`
`Loss of Energy Homeostasis
`
`61
`
`Methods of Assessing Drugdnduced Skeletal
`Muscle Damage
`
`Microscopic Analysis of Skeletal Muscle
`
`62
`
`Muscle Function Studies
`
`63
`
`Leakage of Intramuscular Proteins
`
`64
`
`Microdialysis Studies of Individual Muscles
`
`64
`
`Cellular Stress Response
`
`65
`
`15
`
`15
`
`16
`
`'18
`
`49
`
`50
`
`50
`
`57
`
`57
`
`57
`
`58
`
`62
`
`Techniques to Assess the Mechanisms of Muscle Damage
`
`66
`
`Models oflvluscle Damage
`
`56
`
`Techniques to Show Changes in Muscle Calcium Content
`
`66
`
`Markers oflncreasea‘ Free Radical Activity
`
`67
`
`Methods of Measuring Cellular Energy Levels
`
`67
`
`Conclusions
`
`Acknowledgments
`
`References
`
`67
`
`57
`
`68
`
`Astrazeneca Ex. 2087 p. 4
`
`

`
`Cements
`
`V
`
`13: METHQDS TU ASSESS PAIN, IRRITATION, AND
`MUSCLE DAMAGE FQLLQWING INJECTIONS
`
`In Vitro Methods far Evaluating
`Intravascular Hemolysis
`
`Jaseph F. Krzyzaniak and Sanmef H. 3/aikowsky
`
`Significance
`
`In Vim) Methcbds for Evaluating Henmlysis
`Static Meflzacfs
`8:?
`
`Dynanvfc fvfethgds
`
`83
`
`Con'1pa1‘is<:m of In \fit1"<:~ and In Vivo Hemcolysis Data
`
`Summary 01“ In Vitm Methods
`
`References
`
`Lesion and Eciema Models
`
`Steven C‘. Sutmn
`
`Eciema and Inflammation
`
`Lasiwn M-:)<:ieIs
`
`Rabbit
`
`92
`
`Mice
`
`95
`
`R31‘
`
`E36
`
`Biochemical'Mc»:ieIs
`
`Séarum {3IutamiC~C3Xa!0aC-Mic T1‘ansaminas~&*
`
`9?’
`
`N~Ax:efyI~{3vGhatosanvfniciasa
`
`9?‘
`
`3\»'Iye1Gpar‘0xIdase
`
`9?
`
`Craatine Kinase
`
`£35’
`
`Edema Mocieis
`
`Inducing Edema
`
`105
`
`Exudarive Modefs Qffnflammaiion
`
`105
`
`Vascular Permeabiiity Medals
`
`105
`
`Fooipaci Edenza Ivfadefs
`
`206
`
`Cnrrelation 01“ Models
`
`Rabbi? Lesmn Versus Rabbif E-Ienlarmagez SC{)£”€‘ Mode}
`
`70?
`
`Rabbit fission Versus Rabbit CK Mode}
`
`1308
`
`Ra12bitLesion ‘s'::>I‘sLzs Raf Fooipacl Ecfema Mafia!
`
`:1 09
`
`Rabbit Lesion Versus fiat CK Mode!
`
`‘I09
`
`Rat and Human
`
`110
`
`‘F’?
`
`‘?8
`
`79
`
`85
`
`86
`
`8?"
`
`9?!
`
`91
`
`92
`
`9?’
`
`105
`
`"10?
`
`Astrazeneca Ex. 2087 p. 5
`
`

`
`vi
`
`Injectable Drug Development
`
`Models for Extendecl—Release Formulations
`
`Predicting Muscle Damage from
`Extended-Release Formulations
`
`11'?
`
`Future Directions
`
`Muscle Damage and CK
`
`1112
`
`Gamma Scintigraphy
`
`112
`
`Electron Parametric Resonance and
`
`Nuclear Resonance Imaging
`
`112
`
`Effect of Edema and Lesion on Bioavailabllity H3
`
`Formulation
`
`T13
`
`Conclusions
`
`References
`
`6.
`
`Rat Paw-Lick Model
`
`Pramod K. Gupta
`
`Methodology
`
`Correlation Between Rat Paw-Lick and Other
`
`Pain/Irritation Models
`
`Application of Rat Paw-Lick Model to Screening
`Cosolvent-Based Formulations
`
`Limitations of the Rat Paw-Lick Model
`
`Concluding Remarks
`
`References
`
`7.
`
`Radiopharmaceuticals for the Noninvasive
`Evaluation of Inflammation Following
`Intramuscular Injections
`
`Agatha Feltus, Michael Jay, and Robert M. Beihn
`
`Gamma Scintigraphy
`
`Gamma Cameras
`
`Detectors
`
`I33
`
`Collimators
`
`135
`
`Electronics and Output
`
`136
`
`Computers
`
`137
`
`Tomographic Imaging
`
`139
`
`Quality Control
`
`139
`
`Radiorluclicles and Radiation
`
`Scintigraphic Detection of Inflammation
`
`110
`
`112
`
`114
`
`115
`
`119
`
`120
`
`120
`
`123
`
`126
`
`128
`
`128
`
`131
`
`‘132
`
`132
`
`140
`
`‘ll’-}‘1
`
`Astrazeneca Ex. 2087 p. 6
`
`

`
`Contents
`
`vii
`
`Gallium-67
`
`141'
`
`Radiolabeled Leukocytes
`
`Radiolabeleo’ Antibodies
`
`1'4-3
`
`145
`
`OtherRadiopharmaceuticals
`
`147
`
`Summary
`
`References
`
`A Primer on In Vitro and In Vivo Cytosolic
`Enzyme Release Methods
`
`Gayle A. Brazeau
`
`Rationale for Utilizing Release of Cytosolic Components
`as a Marker of Tissue Damage
`
`Experimental Models
`
`Isolated Rodent Skeletal Muscle Model
`
`General Experimental Overview
`
`159
`
`Isolation, Extraction, and Viability of isolated Muscles
`
`1'60
`
`Muscle Exposure to the Test Formulation
`
`16.2
`
`Incubation Media
`
`164
`
`Cytosolic Enzymes Utilized in Isolated Muscle Studies
`
`1'64
`
`Controls and Data Analysis
`
`164
`
`148
`
`149
`
`155
`
`15?
`
`1559
`
`159
`
`Muscle Cell Culture Methods to Evaluate Muscle Injury
`
`165
`
`General Considerations
`
`165
`
`General Considerations in the Optimization of Experimental
`Cell Culture Systems
`166
`
`Selected Cell Lines in Screening for Drug-Induced Toxicity
`
`168
`
`In Vivo Enzymatic Release Methods
`General Considerations
`169
`
`Animal Models
`
`170
`
`Quantification of Tissue Damage
`
`1?)‘
`
`Conclusions
`
`Acknowledgments
`
`References
`
`169
`
`172
`
`173
`
`'l?3
`
`Histological and Morphological Methods
`
`177
`
`Bruce M. Carlson and Robert Palmer
`
`Basic Principles Underlying Morphological Analysis
`
`Techniques of Morphological Analysis
`
`179
`
`180
`
`Astrazeneca Ex. 2087 p. 7
`
`

`
`viii
`
`Injectabie Drug Development
`
`Electron Microscopic Methods
`
`Histoiogicai Methods
`
`‘I83
`
`Histochernicai Methods
`
`1'85
`
`irnmunocytochemicai Methods
`
`Neuromuscuiar Staining Methods
`
`180
`
`187
`
`189
`
`Summary of Strengths and Limitations of
`Morphological Techniques in Assessing
`Muscle Damage After Injections
`
`References
`
`10.
`
`Conscious Rat Model to Assess Pain
`
`Upon Intravenous Injection
`
`John M. Marcek
`
`Experimental Procedures
`
`Experiment I
`
`Experiment?
`
`Experiment 3
`
`Experiment 4
`
`Experiment 5
`
`Experiment 6
`
`Experiment 7
`
`196
`
`19?
`
`1'9?
`
`197
`
`197
`
`197
`
`1.98
`
`Statistical Anaiyses
`
`198
`
`Results
`
`Discussion
`
`Applications
`
`Summary and Conclusions
`
`Acknowledgments
`
`References
`
`C: APPROACHES IN THE DEVELOPMENT OF
`
`LESS-PAINFUL AND LESS-IRRITATING INJECTABLES
`
`1'1.
`
`Cosolvent Use in Injectable Formulations
`
`Susan L. Way and Gayle Brazeau
`
`Commonly Used Solvents
`
`Poiyethyiene Giycois
`
`219
`
`Propylene Giycoi
`
`223
`
`Ethanoi
`
`225
`
`‘I90
`
`191
`
`193
`
`‘I95
`
`198
`
`204-
`
`209
`
`210
`
`2'11
`
`211
`
`215
`
`218
`
`Astrazeneca Ex. 2087 p. 8
`
`

`
`Cantenig
`
`ix
`
`Gfycerm 226
`
`Cremophors
`
`22?
`
`Bsnzyf Aiccahof
`Amide Solvents
`
`228
`231*}
`
`D£meth‘yIsuff0m'«:;fe
`
`232
`
`Heme-iytic Potentia} cf Saivents/Casolvents
`
`fn Efitraxln Viva Hemcwlysfs Comparisens
`
`23?
`
`Muacle Damage
`
`C0sc:sivent—Re1ated Pain cm Injection
`
`Cosafvenfs Kmzrwn ta Cazrse Pain
`
`2345
`
`Methods fa Minimize Pain
`
`2%?
`
`Canclusiens
`
`References
`
`12.
`
`Prodrugs
`
`Lassie Prokaf and Katalin Prcakai-Tatrai
`
`Design of Fredrugs
`
`Specific: Ehszampies of Pmdmgs Develaped U3 Impr<:we
`Water Soiubiiity czf Injeciables
`
`Anticancer‘ Agents
`
`2?’:-if
`
`Carma! Newaus System Agents
`
`.5383
`
`Other Drugs
`
`2388
`
`Conclusions
`
`Refemnces
`
`13.
`
`Complexatian-“Use of Cyclodaxtrins 1:0
`Improve Pharmaceutical Pmperties of
`Intramuscular Formulations
`
`Marcus E. Brewster and Tharsieinn Lofésscin
`
`Cyciovdextrins
`
`Preparation 01“ Cyclodextrin Cxzmtlplexes
`
`Charactarizatian Q1” Cyciodextrin Complexes
`
`Use 01” Cyclodextrins in IN! Fcsrmulaticms
`
`Methodofogies
`
`319
`
`I'M Taxicfty of Cycladaxfrins and Their Dezivzitéves
`
`320
`
`Use of Cyc1e::dextn'ns fa Repface: Toxic Excfpienrs
`in {M Fm*muIat2"an5
`333
`
`Use of Cyciadextrins to Reduce Intrinsic
`£?rug—Re31afe::f Taxfcizy
`325
`
`23?.
`
`252-2
`
`245
`
`250
`
`251
`
`26?
`
`287
`
`273
`
`295
`
`297
`
`307
`
`Astrazeneca Ex. 2087 p. 9
`
`

`
`lnjectable Drug Development
`
`Conclusions and Future Directions
`
`Acknowledgments
`
`References
`
`‘I4.
`
`Liposomal Formulations to Reduce
`Irritation of Intramuscularly and
`Subcutaneously Administered Drugs
`
`Farida Kaclir, Christien Oussoren, and Dean J. A. Crommelin
`
`Liposomes: A Short introduction
`
`Liposomes as Intramuscular and Subcutaneous
`Drug Delivery Systems
`
`Studies on Reduction of Local Irritation
`
`Studies on the Protective Effect After
`IntramuscularAdministration
`342
`
`Studies on the Protective Effect After lntradermal and
`Subcutaneous Administration
`345
`
`Discussion
`
`Conclusions
`
`References
`
`'15.
`
`Biodegradable Microparticles for the
`Development of Less—Painful and
`Less-Irritating Parenterals
`
`Elias Fattal, Fabiana Quaglia, Pramod Gupta, and Gayle Brazeau
`
`Rationale for Using Microparticles in the Development
`of Less—Painful and Less—Irritating Parenterals
`
`Poly(Lactide—co-Glycolide] Microparticles as Delivery
`Systems in the Development of Less—Painful and
`
`Less-Irritating Parenterals
`357
`
`Polymer Selection
`
`Microencapsulation Technique
`
`360
`
`Drug Release
`
`366
`
`Sterilization
`
`368
`
`Residual Solvents
`
`368
`
`Stability of the Encapsulated Drug and
`Microparticle Products
`369
`
`329
`
`330
`
`330
`
`337
`
`338
`
`340
`
`341
`
`349
`
`350
`
`351
`
`355
`
`356
`
`357
`
`Protection Against Myotoxicity by Intramuscularly/
`Subcutaneously Administered Microparticles
`
`370
`
`Astrazeneca Ex. 2087 p. 10
`
`

`
`Contents
`
`xi
`
`Conclusions
`
`References
`
`16.
`
`Emulsions
`
`Pramod K. Gupta and John B. Cannon
`
`Rationale for Using Emulsions for Reducing Pain and
`Irritation upon Injection
`
`Potential Mechanisms of Pain on Injection
`
`Case Studies
`
`Proplofol (D1'priVan®)
`384
`
`Diazeparn
`Etom i da te
`
`388
`
`382
`
`Pregnanolone(Eltanolone®)
`
`388
`
`Methohexital and Thiopental
`
`389
`
`Amphotericln B
`
`Clarithromycln
`
`390
`
`391‘
`
`Challenges in the Use of Emulsions as Pharmaceutical
`Dosage Forms
`
`Physical Stability
`
`393
`
`393
`Efficacy
`Dose Volume
`
`Other Issues
`
`394
`
`394
`
`Conclusions
`
`References
`
`D: FUTURE PERSPECTIVES IN THE DEVELOPMENT OF
`
`LESS-PAINFUL AND LESS-IRRITATING INJECTABLES
`
`'17.
`
`Formulation and Administration Techniques
`to Minimize Injection Pain and Tissue
`Damage Associated with Parenteral Products
`
`Larry A. Gatlin and Carol A. Gatlin
`
`Formulation Development
`402
`Preformulatlon
`
`Formulation
`
`4134-
`
`Focus on Osmolality, Cosolvents, Oils, and pH
`pH 4-15
`
`4'10
`
`371
`
`372
`
`379
`
`380
`
`381
`
`382
`
`393
`
`395
`
`395
`
`401
`
`402
`
`Astrazeneca Ex. 2087 p. 11
`
`

`
`xii
`
`Injecmbfe Drug Development
`
`Post-Formulation Pmcedurea
`
`pH, Additives, and Solvents
`
`436
`
`Devices and Pm/gicai Marzipuiafmns
`
`41?
`
`References
`
`Index
`
`415
`
`420
`
`423
`
`Astrazeneca Ex. 2087 p. 12
`
`

`
`'1
`
`Challenges in the
`Development of lnjectable
`Products
`
`Michael J. Akers
`
`Biopharinaceutical Products Development
`Lilly Research Laboratories
`Indianapolis, Indiana
`
`The injection of drugs is necessary either because a need exists for a very
`rapid therapeutic effect, or the drug compound is not systemically avail-
`able by non-injectable routes of administration. Early use of injections led
`
`to many adverse reactions because the needs for sterility and freedom
`from pyrogenic contamination were poorly understood (Avis 1992]. Al-
`
`though Pasteur and Lister recognized the need for sterilization to eliminate
`
`pathogenic microorganisms during the 18603, sterilization technologies
`did not advance until much later. For example, the autoclave was discov«
`
`ered in 1884, membrane filtration in 1918, ethylene oxide in 1944, high et‘~
`
`ficiency particulate air (HEPA) filters in 1952, and laminar airflow in 1961.
`
`Increases in body temperature and chills in patients receiving injections
`were observed in 1911, which were found in 1923 to be due to bacteria-
`
`produced pyrogens. The science and technology of manufacturing and us-
`
`ing injectahle products have both come a long way since their inception in
`the mid-1850s. However, the assurance of sterility, particularly with in—
`jectable products manufactured by aseptic manufacturing processes, con-
`
`tinues to be tremendously challenging to the parenteral drug industry.
`
`Injectable products have some very special characteristics unlike any
`other pharmaceutical dosage form [Table 1.1}. Each of these characteristics
`offers unique challenges in the development, manufacture, testing, and use
`
`of these products. These will be discussed more specifically in later sec-
`
`tions of this chapter.
`
`AstraZeneca Ex. 2087 p. 13
`
`

`
`4
`
`injectable Drug Development
`
`Table 1.1. Special Characteristics of and Requirements tor Injectable
`Dosage Forms
`
`-
`
`v
`
`0
`
`-
`
`0
`
`0
`
`-
`
`Toxicologicaliy safe——Inany potential formulation additives are not sufficiently safe for in-
`jectable drug administration
`
`Sterile
`
`Free from pyrogenic (including enciotoxin} contamination
`
`Free from foreign particulate matter
`
`Stahle——~not only physically and chemically but also microhiologically
`
`Compatible with intravenous admixtures if indicated
`
`isotonic
`
`GENERAL CHALLENGES
`
`From a formulation development standpoint, the injectable product for»
`mulation must be as simple as possible. As long as there are no major
`stability, compatibility, solubility, or delivery problems with the active in-
`gredient, injectable product formulation is relatively easy to accomplish.
`Ideally, the formulation will contain the active ingredient and water in a ve-
`
`hicle [e.g., sodium chloride or dextrose] that is isotonic with bodily fluid.
`Unfortunately, most active ingredients to be injected do not possess these
`ideal properties. Many drugs are only slightly soluble or are insoluble in
`aqueous media. Many drugs are unstable for extended periods of time in
`solution and even in the solid state. Some drugs are very interactive with
`surfaces such as the container/closure surface, surfaces of other formula-
`
`tion additives, or surfaces of administration devices.
`
`There are three interesting phenomena that make injectable drug for-
`
`mulation, processing and delivery so complicated compared to other phar-
`maceutical dosage forms:
`
`1.
`
`There are relatively few safe and acceptable formulation addi-
`tives that can be used. If the drug has significant stability, solu-
`
`bility, processing, contamination, and/or delivery problems, the
`
`formulation scientist does not have a plethora of formulation
`
`materials that can be used to solve these problems.
`
`2.
`
`In non-parenteral processing, because of the frequent potential
`
`for powder toxicology Concerns, the process is set up to protect
`
`personnel from the product. In injectable product processing, the
`opposite exists—-the process is set up to protect the product from
`
`personnel because the major sources of contamination are people.
`
`Astrazeneca Ex. 2087 p. 14
`
`

`
`Challenges in the Development of Injectable Products
`
`5
`
`3. When a manufacturer releases a non—injectable dosage form to
`
`the marketplace, the ultimate consumer takes that dosage form
`
`from its package and Consumes it. Because there is little manip-
`ulation of the non-injectable dosage form, potential problems
`created by the consumer of these products are infrequent. How-
`ever, most injectable dosage forms experience one or several ex-
`tra manipulations before administration to the patient. Inj ectable
`drug products are withdrawn from vials or ampoules, placed in
`administration devices, and/or combined with other solutions,
`
`and they are sometimes combined with other drugs. The point
`here is that something is usually done to the injectable product
`that can potentially affect its stability or solubility, or another
`performance factor; such manipulations are done beyond the
`control of the manufacturer. Yet when problems occur, e.g., sta-
`bility or solubility issues, the manufacturer is responsible for
`solving them even though the manufacturer did not cause them.
`
`SAFETY CONCERNS
`
`Drug products administered by injection must be safe from two stand-
`
`points: ['1] the nature of the formulation components of the product and
`
`{2} the anatomical/physiological effects of the drug product during and af«
`ter injection.
`
`Compared to other pharmaceutical dosage forms, there are relatively
`few formulation additives a formulation scientist can choose from to solve
`
`solubility and/or stability problems, maintain sterility, achieve and mairr
`
`tain isotonicity, extend or control the release of drugs from depot injec-
`tions, or accomplish some other need from a formulation standpoint (e.g.,
`bulking agent, viscosity agent, suspending/emulsifying agent). Because of
`
`the irreversibility of the injectable route of administration and the immedi-
`
`ate effect and Contact of the drug product with the bloodstream and sys-
`temic circulation, any substance that has potential toxic properties, either
`
`related to the type of substance or its close, will either be unsuitable for
`
`parenteral administration or will have restrictions for the maximum
`
`amount to be in the formulation. For example, the choices of antimicrobial
`preservative agents for parenteral administration are very limited, and
`
`even those agents that are acceptable have limits on how much of the agent
`
`can be contained in a marketed dosage form. Similar restrictions exist for
`antioxidant agents, surface active agents, solubilizers, cosolvents, and
`
`other stabilizers (e.g., disodium ethylenediaminetetraacetic acid [EDTA]).
`
`There are many potential clinical hazards that may result from the ad-
`
`ministration of drugs by injection [Duma et al. 1992) (Table 1.2]. Several of
`
`these hazards [e.g., hypersensitivity reactions, particulate matter, phlebitis)
`
`AstraZeneca Ex. 2087 p. 15
`
`

`
`6
`
`Injectable Drug Development
`
`Table 1.2. Clinical Hazards of Parenteral Administration
`
`Air emholi
`
`I
`
`limited to IV or IA [intra-arterial) usage
`
`Bleeding
`
`0
`
`Usually related to patient's condition
`
`Fever and Toxicity
`
`*
`
`0
`
`Local or systemic
`
`Secondary to allergic or toxic reaction
`
`Hypersensitivity
`
`9
`
`Immediate and deiayed
`
`Incompatibilities
`
`Can be most threatening if occurring in the vascular compartment
`'3
`Infiltration and extravasation
`
`3
`
`Limited to IV or IA usage
`
`Overdosage
`
`-
`
`Drugs or fluids
`
`Particulate matter
`
`- Most serious in IV or IA administration
`
`'
`
`Can cause foreign body reaction
`
`Phlehitis
`
`I
`
`Usually with IV administration
`
`Sepsis
`
`° May be localized, systemic, or metastatic
`
`Thrombosis
`
`0
`
`Limited to IV or IA administration
`
`can be directly related to formulation and/or packaging components. For
`
`example, some wel1—l<11own hypersensitivity reactions exist with the use of
`bisulfites, phenol, thimerosal, parabens, and latex rubber.
`
`MICROBIOLOGICAL AND
`
`OTHER CONTAMINATION CHALLENGES
`
`There are three primary potential contamination issues to deal with. The
`first is to achieve and maintain sterility. Sterility, obviously, is the uniquely
`premier attribute of a sterile product. The concept of sterility is intriguing
`
`Astrazeneca Ex. 2087 p. 16
`
`

`
`Challenges in the Development of Injectable Products
`
`7'
`
`because it is an absolute attribute, i.e., the product is either sterile or not
`
`sterile. The achievement, maintenance, and testing of sterility involve chal-
`lenges that occupy the time, energy, and money of thousands of people and
`numerous resources. Sterility, by definition, is simp1e—the absence of mi-
`
`crobial life. However, how does one prove sterility? Compendial sterility
`tests use a very small sample from a much larger product population. How
`confident can one be of the sterility of each and every unit of product
`
`based on the test results of a very small sample size? Sterility essentially
`cannot be proved; it can only be assured. This is a huge challenge to the
`parenteral drug and device industry.
`Sterility can be achieved by a variety of methods, including saturated
`steam under pressure [the autoclave), dry heat, gases such as ethylene ox-
`ide and vapor phase hydrogen peroxide, radiation such as cobalt 60
`gamma radiation, and aseptic filtration through at least 0.2 pm filters. Dif-
`
`ferent types of materials and products are sterilized by different methods.
`
`For example, glass containers are usually sterilized by dry heat; rubber clo-
`
`sures and filter assemblies by saturated steam under pressure; plastic and
`
`other heat labile materials by gaseous or radiation methods; and final
`product solutions either by saturated steam under pressure {if the product
`
`can withstand high temperatures], or, more commonly, by aseptic filtra-
`tion. Each of these sterilization procedures must undergo significant study
`(process validation) in order to ensure that the method is dependable to a
`
`high degree of assurance to sterilize the material/product in question un-
`
`der normal production conditions. Great challenges exist in performing
`
`sterilization process validation and monitoring. There are also continuous
`efforts to find newer or better sterilization methods to increase the conve-
`
`nience and assurance of sterility (Akers et al. 1997].
`
`Injectable products must be free from pyrogenic contamination. Pyro-
`gens are metabolic by-products of microbial growth and death. Pyrogenic
`contamination must be prevented since the most common sterilization
`
`methods [e.g., steam sterilization, aseptic filtration) cannot destroy or re-
`
`move pyrogens. Prevention can occur using solutes prepared under pyro-
`
`genic conditions, pyrogen—free water produced by distillation or reverse
`osmosis, pyrogen-free packaging materials where glass containers have
`
`been depyrogenated by validated dry heat sterilization methods, and rub-
`
`ber closures and plastic materials that have been sufficiently rinsed with
`
`pyrogen-free water. The reason for Good Manufacturing Practice (GMP)
`
`requirements for time limitations during parenteral product processing is
`
`to eliminate the potential for pyrogenic contamination, since subsequent
`sterilization of the product will remove microbial contamination but not
`
`necessarily pyrogens.
`
`In sufficient injected amounts, pyrogens can be very harmful to
`
`humans. Pyrogens are composed of lipopolysaccharides that will react with
`the hypothalamus of mammals, producing an elevation in body tempera-
`
`ture [hence its Greek roots {P3/To means fire and gen means beginningll.
`
`Astrazeneca Ex. 2087 p. 17
`
`

`
`8
`
`Injeciabis Drug Development
`
`Depending on the amount of pymgen injected, sthsr physiologicai prob»
`
`isms can occur, including death. Compenciisl tests. both in Vivo [rabbit
`
`mcciei) and in vitro {Limulus amebcczyte lysats), are established ts ensure
`
`that pmducts used in humans are tested and C10 mat contain levels of pyro-
`
`gens that will dc any harm.
`
`In-jectsble products, if injectecl or infused as solutiens, must be free
`from particulate matter contamiiisfisn. Psrticuiste matter in injectables con»
`
`notates at least three important perceptions:
`
`1.
`
`The degree (if product quality and the subsequent refiscticn of
`the quality of the product manufacturer.
`
`2.
`
`The degree of product quality in the “’c1.1stomer’s"' View (patient,
`
`medical pmfessicnal, regulatory agency).
`
`3.
`
`The clinical implications of the potential hazards of particulate
`matter.
`
`The first two psrcepticnsmreiatecl to the manufacturer and to the user :3?
`custcmer—are relatively well-defined and understand in that evidence cf
`
`particulate matter will trigger a series of reactions, ranging from product
`
`complaints to product recalls and other reguiatory actions. However, the
`third perception, that particulate matter is clinicsliy hasardsus, begs more
`questions and discussion. There is substantial evidence of the adverse
`physislagicai effects of injected particulate matter, but still much ccn3'ec~
`ture regarding the relstisnship between the ciinicral hazard and the type,
`sizs, and number sf particulates (Groves 1993).
`
`STABILITY CHALLENGES
`
`injectabie drugs are administered either as solutions or as dispersed sys~
`terns (suspensions, emulsions, iiposames, other micmpariticuiate systems].
`The majcrity of injectable drugs have some kind of instability problem‘
`Many drugs that are sufficientiy stable in readymtowuse sciutions have some
`stability restricticns such as storage in light-protected packaging systems
`or storage at refrigerated conditions, or there may be formulation ingredi-
`ents that stabilize the drug but can themselves undergo degradation.
`The chemical stability of irijectable pmciucts generaliy involves twc
`primary routes sf degradationwmhycirolytic and sxicistive. Other, less pre-
`dominant, Chemical ciegraclatiaztsn mechanisms of injectsble drugs involve
`racemisation, phcstclysis, and some special types of chemical reactions oc-
`curing with large mclecuies. A majority of injectabls drug products are too
`unstable in scluticn to be marketed as rsady—tc>~use solutions. Instead, they
`are available as sterile solids produced by Iycphilisaticm {frsess—drying) cr
`sterile crystallizaiicnfpcwdsr filiing tschnslogiss. Drugs that can he
`
`Astrazeneca Ex. 2087 p. 18
`
`

`
`Challenges in the Development oflnjectable Products
`
`9
`
`marketed as ready-to-use solutions or suspensions still offer the challenge
`
`of needing suitable buffer systems or antioxidant formulations for long-
`term storage stability. Freeze-dried products can undergo degradation
`during the freezing and/or freeze-drying process and, therefore, require
`
`formulation additives to minimize degradation or other physical-chemical
`instability problems. Drugs sensitive to oxidation require not only suitable
`antioxidants and chelating agents in the formulation, but they also require
`special precautions during manufacturing [e.g., oxygen-free conditions),
`and special packaging and storage conditions to protect the solution from
`
`light, high temperature, and any ingress of oxygen. Stabilization of in-
`
`jectable drugs against chemical degradation offers a huge challenge to for-
`mulation scientists.
`
`Physical stability problems are well-known for protein injectable
`
`dosage forms as proteins tend to self-aggregate and eventually precipitate.
`Many injectable drugs are poorly soluble and require cosolvents or solid
`
`additives to enhance and maintain drug solubility. However, improper
`
`storage conditions, temperature cycling, or interactions with other com-
`
`ponents of the product/package system can all contribute to incompatibil-
`ities resulting, usually, in the drug falling out of solution (manifested as
`haze, crystals, or precipitate]. Again, the formulation scientist is challenged
`with finding solutions to physical instability problems. Such solutions can
`he found with either creative formulation techniques or special handling
`
`and storage requirements.
`Microbiological issues arise with storage stability related to the con-
`tainer-closure system being cap able of maintaining sterility of the product;
`
`the antimicrobial preservative system, if present, still meeting compendial
`
`microbial challenge tests; and the potential for inadvertent contamination
`
`of non-terminally sterilized products and the degree of assurance that such
`
`products will not become contaminated. The concern for microbiological
`purity as a function of product stability has caused the Food and Drug Ad-
`ministration [FDA} and other worldwide regulatory bodies to require man-
`ufacturers of injectable products to perform sterility tests at the end of the
`
`product shelflife or to have sufficient container-closure integrity data to
`
`ensure product sterility over the shelf life of the product.
`
`The compatibility of injectable drugs when combined with one an-
`other and/or combined with intravenous fluid diluents can create signifi-
`
`cant issues for formulation scientists. Unlike solid and semisolid dosage
`
`forms, which are used as they were released from the manufacturer, in-
`jectable dosage forms are usually manipulated by people (pharmacist,
`nurse, physician) other than the ultimate consumer (patient) and are com-
`
`bined with other drug products and/or diluents before injection or infu-
`
`sion. These manipulations and combinations are beyond the control of the
`
`manufacturer and can potentially lead to an assortment of problems.
`
`For example, faulty aseptic techniques during manipulation (e.g., reconsti-
`
`tution, transfer, admixture) can lead to inadvertent contamination of the
`
`Astrazeneca Ex. 2087 p. 19
`
`

`
`10
`
`Injectable Drug Development
`
`final product. In addition, drug combinations and additions to certain
`
`intravenous diluents can lead to physical and chemical incompatibilities. It
`is a great challenge to the injectable product formulator and Quality Con-
`trol (QC) management to anticipate these potential problems and do what-
`ever can be done to avoid or eliminate them.
`
`SOLUBILITY CHALLENGES
`
`Many drugs intended for injectable administration are not readily soluble in
`
`water. Classic examples include steroids, phenytoin, diazepam, ampho~
`tericin B, and digoxin. While most insolubility problems can be solved, they
`
`usually require a great amount of effort from the formulation development
`scientist. if a more soluble salt form of the insoluble drug is not available
`
`[e.g., poor stability, difficulty in manufacture, cost, etc), then two basic for-
`
`mulation approaches can be attempted. One involves using formulation ad-
`
`ditives such as water miscible cosolvents, complexating agents (such as
`
`cyclodextrin derivatives), and surface active agents. If none of these addi-
`tives work, then the other approach involves the formulation of a more
`
`complex dosage form such as an emulsion or liposome. Table 1.3 lists the
`
`most common approaches for solving solubility problems with injectable
`
`drugs.
`
`Table 1.3. Approaches for Increasing Solubility
`
`Salt formation [~‘l000>< increase}
`
`pH adjustment
`
`Use of‘ cosolvents {—1000>< increase)
`
`Use of surface-active agents [~ IODX increase]: e.g., polyoxyethylene sorbitan monooleate
`(ill to 0.5%) and polyoxyethylene-polyoxypropylene ethers (0.05 to 0.25%)
`
`Use of complexing agents [~50D>< increase]: e.g., E3‘CyCi‘0dEXU'lI'lS and polyvinyl pyrrolldone
`(PVP)
`
`Microemulsion formulation
`
`Liposome formulation
`
`Mixed micelle formulation [bile salt + phospholipid)
`
`"Heroic" measures: eg.. for cancer clinical trial formulations. use dimethylsulfoxide
`[DMSCI], high concentrations of surfactants, polyols, alcohols, fatty acids. etc.
`
`Astrazeneca Ex. 2087 p. 20
`
`

`
`Challenges in the Development of Injectable Products
`
`11
`
`PACKAGING CHALLENGES
`
`A formulator can create an excellent injectable formulation that is very sta—
`
`ble, easily manufacturable, and elegant. Yet the formulation must be com-
`
`patible with a packaging system. Currently, the most common injectable
`packaging systems are glass vials with rubber closures and plastic vials
`
`and bottles with rubber closures. Glass-sealed ampoules are not as popu-
`
`lar as in the past because of concerns with glass breakage and particulates.
`
`Other packaging systems include glass and