Topics in
`Pharmaceutical
`Sciences 1993
`
`Proceedings of the 53rd International Congress
`of Pharmaceutical Sciences of F.I.P
`held in Tokyo Japan 510 September 1993
`
`Edited by
`Crommelin
`Sciences ol RIP
`Scientific Secretary of PIP and Secretary of the Board of Pharmaceutical
`Sciences Utreeht University The Netherlands
`Institute for Pharmaccutical
`Professor of Pharmaceutics Utrecht
`
`Midha
`
`Sciences of F.I.P
`
`the Department of Psychiatry
`and Medicine University of Saskatchewan
`Canada
`
`Chairman of the Board of Pharmaceutical
`and Associatc Memher 01
`
`Professor of Pharmacy
`
`Colleges of Pharmacy
`
`Nagai
`
`Scientific Programme Chairman Professor and Chairman of the Department of Pharmaceutics
`ceutical Sciences Hoshi University Tokyo Japan
`
`Faculty of Pharma
`
`International Pharmaceutical Federation
`Féddration Internationale Pharmaceutique RI
`The Hague
`
`nsedphurm Scientific Publishers Stuttgart 1994
`
`WIT bLuctI
`DATE ____________
`DAWN HILLIER RMR CRR
`
`ALKERMES Exh. 2033
`Luye v. Alkermes
`IPR2016-1096
`
`

`

`Chapter 32
`
`471
`
`Parenteral Products Design and Optimization Including Freeze
`Drying
`
`Deluca
`
`University of Kentucky College of Pharmacy
`
`Lexington KY 40536 USA
`
`INTRODUCTION
`
`parenteral product can be defined as
`
`sterile drug solution or suspension
`
`that is packaged in manner suitable for administration by hypodermic injection either
`
`in the form prepared or following the addition of
`
`suitable solvent or suspending
`
`agent
`
`The delivery nf drugs via the parenteral
`
`routes of administration has
`
`steadily increased
`
`over
`
`the past
`
`few decades due to the inherent advantages
`
`of
`
`reaching
`
`the systemic circulation quickly
`
`The use of
`
`the parenteral
`
`routes will
`
`continue to increase and will even proliferate due to both the research in targeted
`
`site-specific delivery and the products derived from biotechnology
`
`The successful
`
`formulation of an
`
`injectable preparation requires
`
`broad
`
`knowledge of physical chemical and biological principles as well as expertise in the
`
`application of these principles
`
`Such knowledge
`
`and expertise are required to effect
`
`rational decisions regarding the selection of
`
`suitable vehicle
`
`aqueous
`
`nonaqueous or cosolvent
`
`added substances antimicrobial agents antioxidants
`
`buffers chelating agents and tonicity contributors and
`
`the appropriate container
`
`and container components
`
`The majority of parenteral products are aqueous solutions preferred because
`
`of their physiologic compatibility and versatility with regard to route of administration
`
`However cosolvents or nonaqueous substances are often required to effect solution
`
`or stability
`
`Furthermore the desired properties are sometimes attained through the
`
`use of
`
`suspension or an emulsion
`
`Although each of
`
`these dosage forms have
`
`distinctive characteristics and formulation requirements
`principles are common It
`
`is important to recognize that the pharmaceutical products
`
`certain physical-chemical
`
`

`

`472
`
`Chapter 32
`
`derived from biotechnology are on the increase and the formulation of these proteins
`
`and peptides requires some unique skills and novel approaches
`
`The general
`requirements of
`all dosage forms namely safety effectiveness stability and reliability However
`the bodys most protective barriers and come into
`
`parenteral product include those mandated for
`
`for
`
`those products which circumvent
`
`contact with internal body compartments sterility freedom from pyrogens clarity and
`
`isotonicity become distinctive requirements Therefore the design and optimization
`
`of parenteral products must be approached
`
`around
`
`microcontamination
`
`control
`
`theme i.e freedom from microbial pyrogenic and particulate contamination
`
`STERILITY
`
`While
`
`sterility
`
`is the complete
`
`absence of microorganisms
`
`sterilization is
`
`probability function that the treatment will
`
`render
`
`product
`
`free of microorganisms
`
`Since sterility
`
`testing is destructive it
`
`involves only
`
`small fraction of the total batch
`
`which shows that at
`
`contamination level of
`
`in
`
`This is illustrated in Table
`thousand the batch would be accepted 98% of the time and even at
`batch would be accepted 82% of the time To pass the batch with 95% confidence
`the contamination level would have to be above 15% Hence the official
`
`level
`
`the
`
`sterility
`
`test
`
`cannot
`
`be used to extrapolate with any certainty to the unsampled containers
`
`Statistically the chances of
`
`failing
`
`batch are very low Therefore assurance
`
`of
`
`sterility must be designed into and implemented during the processing of
`
`parenteral
`
`product
`
`TABLE
`
`0.1
`
`0.001
`0.999
`0.98
`
`Probability of Acceptance
`of Batches
`With Relationships
`to Sample Size
`
`Contaminated Units in Batch
`10
`
`20
`
`0.01
`0.99
`0.82
`
`0.05
`0.95
`0.36
`
`0.2
`
`0.8
`
`0.01
`
`0.1
`
`0.9
`0.12
`
`CN
`
`50
`
`0.5
`
`0.5
`0.00001
`
`Where
`the proportion of contaminated units in
`represents
`the proportion of non-contaminated
`is the probability of selecting
`20
`20 consecutive
`
`sterile units
`
`batch and
`
`

`

`Chapter 32
`
`473
`
`Agents with antimicrobial activity must be added to preparations packaged in
`
`multiple-dose containers unless prohibited by the monograph or unless the drug itself
`
`is bacteriostatic
`
`They are often added to unit-dose solutions which are not sterilized
`
`at the terminal stage of their manufacture
`
`In the case of multiple-dose preparations
`
`the antimicrobial
`
`agent
`
`is
`
`required
`
`as
`
`bacteriostat
`
`to
`
`inhibit any microbes
`
`accidentally introduced while withdrawing doses Antimicrobial agents may also serve
`
`role as adjuncts in aseptic processing of products e.g prefilled syringes where
`
`there may be product exposure during transfer filling
`
`and stoppering operations
`
`Thus should
`
`trace
`
`contamination occur during the manufacturing process
`
`the
`
`antimicrobial agent may render
`
`the product sterile
`
`Consideration must
`
`be
`
`given
`
`to the
`
`stability and effectiveness
`
`of
`
`the
`
`antimicrobial agent
`
`in combination with the active
`
`ingredient and other added
`
`substances
`
`Many papers have been published describing the incompatibilities or
`
`binding of preservatives with surfactants pharmaceuticals and rubber closures
`
`13-8
`
`The effectiveness of antimicrobial agents
`
`can be tested by challenging
`
`the
`
`product with selected organisms to evaluate the bacteriostatic or bactericidal activity
`
`in
`
`formulation The challenge test described
`
`in the USP
`
`should be performed
`
`with the formulation throughout and near the end of the expiration date to ensure that
`
`adequate levels of preservative
`
`are still available
`
`PYROGENS
`
`Some lipopolysaccharide materials of bacterial origin can associate with varying
`
`amounts of proteins and phospholipids This stimulates the production of endogenous
`
`pyrogens giving rise to febrile and other undesirable
`
`pharmacological
`
`responses
`
`Pyrogens are the byproducts of bacterial contamination and must be guarded against
`
`in parenteral products Water
`
`ingredients container components administration sets
`
`and medical
`
`devices
`
`used in the preparation
`
`packaging
`
`and administration of
`
`parenteral products must be maintained sterile and free of pyrogens Chemically
`
`pyrogens are water-soluble and heat
`
`resistant so they are not easily removed once
`
`introduced
`
`Endotoxin
`
`derived from gram negative
`
`coli will produce
`
`pyrogenic
`
`reaction in the rabbit at
`
`concentration of
`
`pg per Kg
`
`The major sources of endotoxin or pyrogenic contamination are the product
`
`components water excipients and the container processing equipment and human
`
`emissions Pyrogens can be avoided in parenteral products by
`
`reducing airborne
`
`

`

`474
`
`Chapter 32
`
`bacterial contamination in processing areas
`
`using freshly distilled water Ic having
`
`rigid specifications for ingredients
`
`compounding and sterilizing the solution within
`
`24 hour period and
`
`rinsing equipment containers and closures with water for
`
`injection and sterilizing within 24 hours
`
`CLARITY
`
`Freedom from particulate contamination is one specification essential to ensure
`
`function and integrity of
`
`the product
`
`and safety for the patient The attribute of
`
`freedom from undesirable particulates must not only be built
`
`into the product and exist
`
`when the product
`
`is
`
`released by the manufacturer
`
`but must be maintained during
`
`shipping and storage and upon administration to the patient
`
`The presence of foreign
`
`materials in solutions to be administered directly into the bloodstream has been of
`
`deep concern to drug-safety regulators manufacturers clinicians and consumers Not
`
`only do particulates constitute potential adverse clinical consequences but
`
`the quality
`
`of the product becomes
`
`suspect when undissolved material
`
`is observed
`
`An appreciation of
`
`the magnitude
`
`of
`
`the problem of particulates can be
`
`illustrated by an example of purity and impurity of material
`product that is
`99.99% pure contains only 0.01% impurity or 100 parts per million ppml Although
`
`this generally is
`
`tolerable amount of impurity even on
`
`100-fold smaller scale of
`
`ppm i.e mg/liter such
`
`level of insoluble impurity or contamination is equivalent
`
`to 120000 particles assuming
`
`density of
`
`25 pm in diameter This level of
`
`particulate contamination is well above the USP allowable limit
`
`for
`
`intravenous
`
`solutions
`
`The number of spherical
`
`particles per milligram of substance
`
`can be
`
`calculated
`
`from the formula
`
`Particles/mg
`
`191
`
`1o9
`
`dD3
`
`where
`
`is the density of
`
`the particle and
`
`is the diameter in micrometers Table
`
`shows the number of solid non-porous
`
`spherical particles in milligram of insoluble
`
`impurity or contaminant at various diameters and densities
`
`Particulate matter
`
`in parenteral solutions has been
`
`matter of concern to
`
`regulatory agencies and standard setting bodies for
`
`number of years 110 Official
`
`standards for particulate matter in parenteral solutions are shown in Table
`
`

`

`Chapter 32
`
`475
`
`TABLE
`
`Number of Solid Spherical Particles
`as
`Function of Density
`
`in Milligram of Insoluble Material
`
`Diameter
`pml
`
`10
`25
`50
`
`0.5
`
`3.8x109
`3.0x107
`3.8x106
`2.4x105
`3.0x104
`
`Density
`
`1.0
`
`1.9x109
`1.5x101
`1.9x106
`1.2x105
`1.5x104
`
`1.5
`
`1.3x109
`1.OxlO
`1.3x108
`0.BxlOt
`1.0x104
`
`The quantity
`
`mg/liter represents
`
`ppm
`
`TABLE
`
`Comparison of Official Standards
`Solutions
`
`for Particulate Matter
`
`in Parenteral
`
`Pharma
`
`copeia
`
`Method
`
`Microscope
`
`Instrumental
`
`2pm
`
`5pm
`
`Opm
`
`2Opm
`
`25pm
`
`1.1SF XXII
`19901
`
`LVP
`
`SF 1988
`
`SVP
`
`Light
`
`Extinction
`
`Light
`Extinction
`
`Electrolyte
`
`resistance
`
`500 max
`per ml
`
`1000
`max per
`mi
`
`80 max
`per ml
`200 max
`per ml
`
`50 max
`per ml
`
`10000
`max per
`container
`
`max
`per ml
`
`1000
`max per
`container
`
`LVP/SVP
`
`JP
`11986
`
`EF II In
`discussloni
`
`Light
`
`Obscuration
`
`100 mex
`per ml
`
`max
`per ml
`
`50 max
`per ml
`
`max per
`ml
`
`OTHERS Prectlcelly
`
`free of particles under suitable visual conditions
`
`The sources
`
`of microbial
`
`pyrogenic
`
`and particulate contamination can
`
`be
`
`categorized
`
`broadly into the following
`
`The environment
`
`The product
`
`components
`
`The personnel
`
`It
`
`is not difficult
`
`to understand that contamination generated from any of these
`
`

`

`476
`
`Chapter 32
`
`It
`
`is not difficult
`
`to understand
`
`that contamination generated from any of these
`
`sources will contribute to the contamination of one or both of the others Therefore
`
`the design utilization and sanitization of
`
`facility
`
`and the equipment must be
`
`adequate to ensure minimum levels of contamination during processing of the product
`
`components by people
`
`Strict
`
`regulations of good manufacturing practices exist
`
`for
`
`these
`
`three
`
`categories
`
`These are addressed in the Part 211 of the Current Good Manufacturing
`
`Practice for Finished Pharmaceuticals Part 21
`
`of the Current Manufacturing Practice
`
`for Large Volume Parenterals
`
`and
`
`the 1987 Guideline
`
`on Sterile Drug Products
`
`Produced by Aseptic Processing
`
`These categories will be briefly discussed
`
`FACILITIES
`
`The CGMP requirements are found in the following sections
`
`Section
`
`211.42
`
`Must be separate or defined areas of operation to prevent
`
`contamination and that for aseptic processing there be as appropriate an air supply
`
`filtered through HEPA filters under positive pressure and systems for monitoring the
`
`environment and maintaining equipment used to control aseptic conditions
`
`Section 211.46 Equipment for adequate control over air pressure microorganisms
`
`dust humidity and temperature be provided where appropriate and that air filtration
`
`systems including pre filters
`
`and particulate matter air
`
`filters
`
`be used when
`
`appropriate on air sup piles to production areas
`
`In parenteral product manufacturing there are various areas of operation which
`
`require separation and control with each area designated
`
`according
`
`to the levels of
`
`air quality These areas are classified as critical and controlled
`
`Critical Areas
`
`critical
`
`area is one in which
`
`the sterilized dosage form containers
`
`and
`
`closures are exposed to the environment Activities that are conducted
`
`in this area
`
`include manipulations of
`
`these
`
`sterilized materials/product
`
`prior
`
`to and during
`
`filling/closing operations
`
`These operations are conducted
`
`in what is typically called
`
`the aseptic core area The specifications for critical areas are
`
`

`

`Chapter 32
`
`477
`
`Airborne Particle Content
`
`Class 100-no more than 100 particles 0.5 pm and
`larger when measured one foot from the work site
`
`Velocity of Air
`
`90 ft./min
`
`20%
`
`Change of Air
`
`60-80/hr
`
`Airborne Microbes
`
`no more than
`
`colony forming unit
`
`per 10 cu ft
`
`Pressure Differential
`
`0.05 I20 relative to adjacent area
`
`Controlled Areas
`
`Controlled areas are those in which unsterilized product
`
`in process materials
`
`and containerlclosures
`
`are prepared
`
`This includes
`
`areas where components are
`
`compounded and where components in process materials drug products and contact
`
`surfaces of equipment containers and closures after final
`
`rinsing of such surfaces are
`
`exposed to the plant environment The environment should be of
`
`high microbial and
`
`particulate quality in order to minimize the level of particulate contaminants in the final
`
`product and to control
`
`the microbiological content bioburden of articles and
`
`components which are subsequently sterilized
`
`There are two levels of controlled areas ultraclean and clean The differences
`
`in these two areas result from the design and location of the HEPA filters in the ceiling
`
`diffusers This will determine whether the area is ultraclean class 10000 or clean
`
`class 100000
`
`These two levels can be achieved with HEPA filters in the ceiling
`
`diffusers and air conditioning units while class 100 can only be achieved with laminar
`
`airflow
`
`Additional specifications for controlled areas are
`
`Airborne microbes
`
`25 CFUs per 10 cu ft
`
`Air changes
`
`at
`
`least 20 per hour
`
`Pressure differential
`
`0.05 H20 relative to adjacent areas
`
`The Parenteral Product manufacturing area can be illustrated in
`
`block diagram
`
`relative
`
`to the environmental control
`
`This is shown in Figure
`
`Besides the
`
`environmental control
`
`the overall
`
`facilities
`
`relative to construction materials layout
`
`and flow of materials and housekeeping must be designed with the concept
`
`of
`
`control and ease of cleanliness
`
`

`

`478
`
`Chapter 32
`
`Fig
`
`Schematic
`illustration
`of controlled environment
`
`areas Pressure differential
`0.05 H20
`between areas
`
`MechanIcal Area
`
`General Area
`
`Clean Area
`
`Adjacent Ultra Clean
`
`and
`
`SteTile CritIcal Area
`
`_________________________
`
`PRODUCT COMPONENTS
`
`Section 211.80 requires in part
`
`the establlshment of written procedures for
`
`the storage handling and testing and approval or rejection of components
`
`Section 211.84 requires in part
`
`that components liable to microbiological
`
`contamination that
`
`is objectionable in view of
`
`their intended use be subjected to
`
`microbiological
`
`tests before use
`
`finished drug product
`
`produced
`
`by aseptic
`
`processing may become
`
`contaminated through use of components which contain microorganisms
`
`Therefore
`
`it
`
`is necessary
`
`to establish the bioburden of the component parts set
`
`limits and then
`
`process the components
`
`in manner which wilt provide
`
`sterile product or not more
`
`then one contaminated unit in million Component parts are generally sterilized by
`
`an appropriate method and then combined
`
`in
`
`sterile environment described earlier
`
`If
`
`the
`
`product
`
`component
`
`is adversely
`
`affected
`
`by heat
`
`then
`
`filtration
`
`sterilization can be employed to render
`
`the component sterile If
`
`the component can
`
`withstand heat
`
`it
`
`can be prepared
`
`as
`
`solution suitable suspension or disperse
`
`system and subjected to steam sterilization To minimize the introduction of pyrogens
`
`there should be rigorous standards
`
`for the acceptance
`
`of components which are
`
`susceptible to pyrogens
`
`Such components
`
`such as natural substances must be
`
`rendered free of pyrogens before using
`
`

`

`Chapter 32
`
`479
`
`CONTAINERS AND CLOSURES
`
`Section 211.94 drug product containers and closures requires In part
`
`that
`
`drug product containers and closures be clean and where indicated by the nature of
`
`the drug sterilized and depyrogenated Standards and testing methods and where
`
`indicated methods of cleaning sterilizing and processing to remove pyrogenic
`
`properties must be written and followed
`
`The requirement
`
`is not
`
`limited to cleaning
`
`to remove
`
`surface debris
`
`The
`
`Parenteral Drug Association has published guidelines on the processing and selection
`of glass containers ill
`
`Various surface treatments are used to improve chemical
`
`resistance
`
`and decrease alkalinity
`
`For example exposing hot containers to sulfur
`
`dioxide reduces sodium content at the surface and
`
`brief treatment with ammonium
`
`bifluoride effectively cleans the surface by dissolving
`
`portion of it Containers and
`
`closures are washed in
`
`controlled environment area to effectively clean the surface
`
`and remove particulates
`
`Following washing the containers and components are
`
`packaged to maintain cleanliness
`
`during transfer to the sterilizers where they will be
`
`rendered sterile and pyrogen free Adequacy of these procedures must be validated
`
`under
`
`actual
`
`conditions
`
`of manufacture utilizing
`
`appropriate challenges with
`
`microorganisms and endotoxin
`
`PERSONNEL TRAINING
`
`Many papers have been written and data presented which show that people are
`
`the major sources
`
`of contamination in parenteral
`
`operations
`
`The emission of
`
`submicron particles 0.3 microns through various movements from standing still with
`
`modest movement to violent exercise increase from i05 to iO7 particles per minute
`
`Microorganisms routinely found in the respiratory tract
`
`in the G.I.T and on the skin
`
`have been isolated in clean rooms which showed no presence of such organisms prior
`
`to people entering the room
`
`Therefore training of personnel
`
`is essential Requirements must be established
`
`for personnel working with parenteral products and especially those involved in clean
`
`room activities
`
`The following hints can be helpful
`
`in establishing training programs
`
`Create an awareness
`
`of bioburdens
`
`through bacteriological monitoring
`
`demonstrations
`
`Show how disinfectants control contamination
`
`

`

`480
`
`Chapter 32
`
`Show why gowning is essential
`
`Establish
`
`gowning procedure
`
`Minimize number of people and their movement in the cleanrooms
`
`Make sure that everything which enters the cleanroom has been sterilized
`
`and/or disinfected
`
`Know how to respond in case of emergencies
`
`Supervisors of parenteral
`
`operation must be responsible for training people to
`
`follow CGMPs and lastly management should educate personnel on how the products
`
`they are preparing are actually used by patients
`
`PROCESS VALIDATION
`
`Section 211 113 control of microbiological contamination requires in part the
`
`establishment and adherence to appropriate written procedures designed to prevent
`
`microbiological
`
`contamination of drug products purporting
`
`to be sterile
`
`Such
`
`procedures must
`
`include validation of any sterilization process
`
`There comes
`
`point in the development process of
`
`product to characterize
`
`the production process and assess its effect on the formulation This requires scale-
`
`up procedures to identify the process and equipment variables and with knowledge
`
`of
`
`the
`
`formulation
`
`and
`
`package
`
`variables
`
`assess
`
`how product quality
`
`and
`
`manufacturing productivity will be affected
`
`In the manufacture of
`
`sterile product
`
`the assurance
`
`that
`
`the finished
`
`product possesses
`
`the desired
`
`quality control
`
`characteristics
`
`depends
`
`on
`
`number of
`
`independent
`
`but
`
`interrelated events
`
`commencing with the initial design of the dosage form and carrying forth through the
`
`process
`
`design and validation
`
`and culminating with the establishment of standard
`
`procedures for manufacturing
`
`To provide for the assurance that all quality attributes will be achieved on
`
`repetitive basis the following are essential
`
`the dosage form is designed with
`
`knowledge of the desired functional and quality control characteristics of the finish
`
`product
`
`Ib the qualification procedures
`
`are adequate
`
`to ensure reliability
`
`of
`
`the
`
`equipment
`
`effectiveness
`
`of
`
`the process
`
`and the
`
`integrity of
`
`the
`
`processing
`
`environment
`
`personnel are trained in contamination control
`
`techniques and dl
`
`there is adequate documentation of all procedures
`
`and tests Such
`
`development
`
`sequence
`
`combined with validation
`
`requirements suggests
`
`formalized program
`
`

`

`Chapter 32
`
`481
`
`culminating in
`
`product that can be reliably processed The process characterization
`
`is
`
`principal step in assuring that the process can be translated to manufacturing on
`
`routine production basis
`
`FORMULATION
`
`STRATEGIES
`
`Earlier it was stated that parenteral dosage forms were on the increase and
`
`would continue to increase because of the research in novel drug delivery systems and
`
`the proliferation of biopharmaceutical products
`
`Novel Drug Delivery
`
`These biodegradable
`
`systems are being designed and developed
`
`to transport
`
`drugs and other agents to target sites for controlled release
`
`The innovative
`
`drug
`
`carriers include biodegradable
`
`polymers fabricated into microspherical matrices and
`
`liposomes which are phospholipid vesicles Several
`
`reasons can be listed for targeting
`
`these systems via injection
`
`They include
`
`Providing high local concentrations and sustained activity
`
`Minimizing undesirable system toxicity
`
`Administration of drugs with short haif-lifes
`
`Improved
`
`patient compliance
`
`Liposomes
`
`As illustrated in Figure
`
`these vesicles
`
`consist of bilayers of
`
`amphipathic phospholipid molecules separated
`
`by an equal number of aqueous
`
`compartments
`
`The water soluble heads of the phospholipid molecules interface with
`
`the aqueous compartments while the water-insoluble fatty acid tails orient back-to-
`
`back to form the lipid bilayers Lipophilic
`
`substances will
`
`localize in the lipid bilayers
`
`while polar
`
`substances
`
`dissolve
`
`in the aqueous
`
`compartments
`
`number of
`
`parenteral
`
`liposome-based products are currently under clinical
`
`testing in the United
`
`States Canada and Europe for the treatment of certain cancers systemic fungal and
`
`viral
`
`infections and parasitic and infectious diseases
`
`Formulation of liposomes is
`
`formidable task because of stability problems of
`
`leakage and agglomeration However
`
`freeze drying in the presence of
`
`hydrophilic
`
`substance
`
`provides
`
`stable dehydrated
`
`form which upon rehydration will restore the
`
`original
`
`integrity of
`
`the vesicle
`
`Apparently
`
`the hydrophilic substance such as
`
`sucrose or dextran will penetrate the aqueous compartments as well as occupy the
`
`external
`
`interstitial
`
`spaces between
`
`the liposomes
`
`This prevents
`
`collapse of the
`
`Ilposomal walls or fusing of the lipid bilayers upon removal of water as well as keeping
`
`the vesicals
`
`separated from one another
`
`

`

`482
`
`Chapter 32
`
`MULTILAMELLAR
`RESOLE
`
`UNILAMELLAR
`VESICLE
`
`Fig
`
`Illustration of
`liposome and
`
`phospholipid
`molecule ref 12
`
`PflO5oLIPD MOLECULE
`
`WATER-INSOLUBLE
`
`TAIL
`
`WATER SOLUBLE
`
`lEAD
`
`CH0--C
`
`ft
`
`Ct%c8
`
`FATlY ACID
`
`Cl%
`
`CnO-- Cac ..
`
`Microspheres
`
`There are synthetic polymeric carriers which release the loaded
`
`drug substances by either diffusion through hydrated pores within the polymer matrix
`
`or by erosion of the polymer The homopolymers and copolymers of polyglycolic and
`
`polylactic acids have been the most widely used carriers for drug delivery These
`
`materials have been used safely as surgical sutures and prosthetic devices and do not
`
`require surgical removal They degrade by
`
`hydrolytic process in soluble monomers
`
`and are eliminated via the kidney
`
`The
`
`structures
`
`of
`
`the poylactide
`
`and polyglycolide
`
`homopolymers
`
`and
`
`copolymers are shown in Figure
`
`Biodegradation
`
`of these polymers depends on
`
`the crystallinity
`
`and molecular weight
`
`Therefore
`
`those polymers which have
`
`crystalline domains will degrade slower than the amorphous forms These polymers
`
`can be formulated into porous and nonporous microspheres Polylactide-co-glycolide
`
`microspheres containing isoproterenol are shown in Figure 4a In an animal study
`
`these microspheres protected the animals from serotonin induced bronchoconstriction
`
`for
`
`least 12 hours while free isoproterenol offered protection for about 30 minutes
`
`peptide calcitonin was incorporated
`
`into the same polymer but
`
`in manner
`
`

`

`to produce porous microspheres illustrated in Figure 4b In an animal study serum
`
`Chapter 32
`
`483
`
`days from single administration while with free peptide
`levels were prolonged for
`baseline levels were achieved in 2-6 hours 14
`
`1Tt
`
`Fig
`
`Structures of poly
`lactide and poly
`glycolide homo and
`co-polymers
`
`Poty 1-Lictide
`
`Peay
`
`I-Lzcddc
`
`Iodide
`
`glyoide
`
`220.C
`
`Poly Otycolide
`
`HO
`
`HO
`
`cH3O
`
`CH3O
`
`PGA
`
`P1_A
`
`Fig 4A Nonporous PLGA
`microsphere
`
`containing
`
`isoproterenol
`
`Fig 4B Porous PLGA
`microsphere
`
`containing
`salmon
`
`calcitonin
`
`

`

`484
`
`Chapter 32
`
`In order to provide safe injectable or
`
`implantable drug delivery systems free
`
`from microbial contamination the fabricated device should be able to withstand some
`
`type of sterilization technique with predictable assurance that the polymer will
`
`remain
`
`effective
`
`Cobalt-GO gamma
`
`radiation offers an expedient means of
`
`terminally
`
`sterilizing polymeric drug delivery systems The concerns are the effect of radiation
`
`on the incorporated agents and the polymer characteristics namely molecular weight
`
`and thermal properties which will effect polymer degradation and release of drug
`radiation dose of 1.8 to 2.6 mRads has been shown to provide
`microorganisms in the sterilization of parenterals 15 In microspheres the residual
`moisture content will undoubtedly influence
`
`the adverse effects of radiation
`
`an overkill of
`
`FREEZE DRYING PROCESS
`
`The types of materials requiring freeze-drying can be classified into three broad
`
`categories
`
`Antibiotics
`
`Natural
`
`and semisynthetic microbial metabolites which
`
`include the penicillins cephalosporins tetracyclines
`
`aminoglycosides
`
`macrolides and polypeptides
`
`Macromolecules Proteins and polypeptides in nature which make up the
`enzymes hormones monoclonal
`
`antibodies and the biologicals and
`
`biological
`
`response modifiers
`
`Other Organic electrolytes
`
`Each of these product types present unique challenges and requirements Most
`of the products comprising the other category are organic electrolytes which exhibit
`eutectic points and supercooling tendencies
`
`and can be formulated and dried In
`
`manner
`
`eutectics
`
`and freeze in the amorphous
`
`Generally antibiotics do not
`
`form true
`
`to avoid melting and collapse
`state 16 Phase transitions during freezing
`drying and temperature treatment can induce crystallization which will affect
`
`nature of the final dried product Macromolecules which presently constitute about
`25% of the parenteral products requiring packaging in the dry form offer the most
`These
`challenges
`from genetic
`the products
`recombinant DNA technology
`
`include
`
`derived
`
`engineering
`
`and
`
`review of the Physicians Desk References
`
`revealed that of the approximately
`130 currently marketed products which are packaged in the dry form two thirds of
`
`the
`
`

`

`Chapter 32
`
`485
`
`these
`
`are
`
`freeze dried
`
`What
`
`is
`
`even more revealing
`
`is
`
`that of
`
`the
`
`19
`
`biopharmaceuticals introduced since 1982 and the 120 undergoing clinical
`
`testing
`
`more than half are in the freeze dried form
`
`The process of freeze drying illustrated in Figure
`
`involves
`
`dissolving the
`
`drug and excipients in
`
`suitable solvent generally water bI sterilizing the bulk
`
`solution by passing it through
`
`bacteria-retentive filter Cc filling
`
`into individual sterile
`
`DISSOLVING
`MATERIAL
`
`ASEPTIC
`FILTRATION
`
`FILLING
`
`FREEZE
`DRYING
`
`Fig.5 Process of
`freeze drying
`
`STABILITY
`
`RAPID SOLUBILITY
`
`ELEGANCE
`
`containers dl freezing the solution by placing the open containers on cooled shelves
`
`in
`
`freeze-drying chamber
`
`and Ce applying
`
`vacuum to the chamber and heating
`
`the shelves
`
`in order to sublime the water
`
`from the frozen state
`
`The desired
`
`characteristics of
`
`freeze-dried pharmaceutical
`
`dosage form include
`
`an intact cake
`
`occupying
`
`the same shape and size as the original frozen mass
`
`sufficient strength
`
`to prevent cracking powdering or collapse Cc uniform color and consistency
`
`Cd sufficient dryness to maintain stability and Ce sufficient porosity and surface area
`
`to permit rapid reconstitution Of course as with any injectable dosage form freedom
`
`from contamination i.e microorganisms pyrogens and particulates is an essential
`
`attribute
`
`The biopharmaceuticals offer the greatest challenges in formulation and design
`
`of freeze dried cycles Cryoprotectants or lyoprotectants are essential
`
`in preventing
`
`damage to the protein during the freeze drying process as well as during storage of
`
`the packaged dried product Additionally
`
`since freeze drying is cost
`
`intensive and
`
`

`

`486
`
`Chapter 32
`
`energy consuming process cycles must be optimized Often the cryoprotectants
`
`employed require drying at
`
`low temperatures to prevent meltback or collapse of the
`
`frozen cake during drying
`
`Therefore it will
`
`become
`
`increasingly important
`
`to
`
`accelerate
`
`freeze drying cycles through the use of mass transfer accelerators
`
`Crvoorotectants in Freeze Drying
`
`Townsend et al illustrated the effect of
`as model protein 17 Figures 6A and
`and Ficoll 70
`branched polymer of sucrose in preventing loss of enzymatic activity
`
`cryoprotectant using Ribonuclease
`show the protection afforded by sucrose
`
`LO
`
`Cu
`Cu
`
`.2
`
`az
`
`Sucrose wiv
`
`flcoll 70 wlv
`
`Figure
`
`Lyoprotectan
`effect of sucrose lAl and Ficoll 181
`dried RNase stored at 45c Solutions containing
`1.5 mg/mI RNase in 0.1
`phosphate buffer were freeze
`dried and stored for 30 days pH 10.01 and 105 days IpH
`for each point
`
`in freeze
`
`6.41
`
`The extent of protection is
`
`illustrated in Figures
`
`and
`
`occurred
`
`rapid loss in activity
`in freeze dried RNase dried at pH 3.0 and 10.0 The results suggested
`buffer salts played
`
`role in the degradation
`
`Figure
`
`shows the loss of activity of
`
`that
`
`

`

`Chapter 32
`
`487
`
`d.eIItIed waler
`
`pH 4.0
`
`pH 3.0
`
`pH 10.0
`
`____________________________________
`100
`
`ill
`
`120
`
`20
`
`40
`
`60
`
`60
`
`1.0
`
`5.8
`
`0.6
`
`0.4
`
`02
`
`IA
`
`Figure
`
`DAYS AT 450
`Fraction of control specific activity for RNase freeze dried
`in distilled water and in phosphate buffer at various pH and
`stored at 45C
`
`Air Dark
`
`Air Light
`
`I1
`
`111
`
`30
`
`Days Stored at 45C
`FigureR ANase freeze dried in pH 10 phosphate buffer without addi
`tives The line graph depicts the fraction of control activity
`total RNase
`and the bar graphs represent
`the fraction of
`soluble monomeric
`concentration
`insoluble aggregate
`
`soluble aggregate
`
`ANase
`
`freeze dried at pH 10 without additives and sealed under
`RNase
`headspace of air
`and argon 17 After 30 days storage at 45C samples stored in the light and dark
`had specific activities that were about 10% of
`initial activity The major Change was
`
`the large increase in insoluble aggregated
`
`protein
`
`Removal
`
`of air prevented
`
`the
`
`formation of
`
`insoluble aggregates
`
`and
`
`reduced
`
`the soluble aggregates
`
`The
`
`cryoprotectants sucrose and Ficoll 70 prevented aggregation during freeze drying and
`
`upon storage in the solid state Aggregation was found to occur via an autooxidative
`
`mechanism and SDS-PAGE confirmed the aggregates as covalently bonded dimers of
`
`RNase
`
`devoid of any enzymatic activity 119
`
`

`

`488
`
`Chapter 32
`
`T083 is an
`
`1gM murine monoclonal
`
`antibody MoAb directed against
`
`lymphocytes and which is presently being tested for its therapeutic efficacy in the
`
`treatment of
`
`renal allograft rejection in human clinical
`
`trials Suitable solution and
`
`freeze dried forms were developed for clinical
`
`trials with the freeze dried form showing
`
`superior stability Sucrose and maltose were found to be effective cryoprotectants
`
`and lyoprotectants for the 1gM MoAb as illustrated by the data in Table
`
`1gM
`
`binding activity as assessed by flow cytometry showed retention in antibody titre for
`loss of titre in 14 months at 4C
`
`over 1.5 years while the solution form showed
`
`There was
`
`no evidence
`
`of particulate matte