Pharmaceutical
`production
`
`An engineering guide
`
`Edited by Bill Bennett and Graham Cole
`
`IChemé
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 1 of 71
`Page 1 of 71
`
`

`

`The information in this book is given in good
`faith and belief in its accuracy, but does not
`imply the acceptance of any legal liability or
`responsibility whatsoever, by the Institution, or
`by the editors, for the consequencesofits use or
`misuse in any particular circumstances. This
`disclaimer shall have effect only to the extent
`permitted by any applicable law.
`
`All rights reserved. No part of this publication
`may be reproduced, stored in a retrieval
`system, or transmitted, in any form or by any
`means, electronic, mechanical, photocopying,
`recording or otherwise, without the prior
`permission of the publisher.
`
`Published by
`Institution of Chemical Engineers (IChemE)
`Davis Building
`165-189 Railway Terrace
`Rugby, Warwickshire CV21 3HQ, UK
`
`IChemE is a Registered Charity
`Offices in Rugby (UK), London (UK) and Melbourne (Australia)
`
`‘C) 2003 Institution of Chemical Engineers
`
`ISBN 0 85295 440 9
`
`Typeset by Techset Composition Limited, Salisbury, UK
`
`Printed by Antony Rowe Limited, Chippenham, UK
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 2 of 71
`Page 2 of 71
`
`

`

`Contents
`
`Preface ........................................................................
`
`v
`
`List of Acronyms ..........................................................
`
`v
`
`Glossary ...................................................................... xi
`
`1.
`
`Introduction .........................................................
`
`1
`
`9
`
`2. Regulatory Aspects ............................................
`2.1
`Introduction .............................................................
`2.2 Key Stages in Drug Approval Process .................. 10
`2.3 Example of Requirements ..................................... 12
`2.4 Post-Marketing Evaluation ..................................... 1
`2.5 Procedures for Authorizing Medicinal
`Products in the European Union ............................ 14
`2.6 European and US Regulatory Perspectives .......... 14
`
`3. Good Manufacturing Practice ............................ 17
`3.1
`Introduction ............................................................. 1
`3.2 GMP Design Requirements ................................... 22
`3.3 GMP Reviews of Design ........................................ 34
`
`4. Validation ............................................................. 38
`4.1
`Introduction ............................................................. 3
`4.2 Preliminary Activities .............................................. 4
`4.3 Validation Master Planning .................................... 44
`4.4 Development of Qualification Protocols and
`Reports ................................................................... 5
`
`IPR2020-00770
`United Therapeutics EX2020
`Page 3 of 71
`
`

`

`4.5 Design Qualification (DQ) ...................................... 53
`4.6
`Installation Qualification (IQ) .................................. 55
`4.7 Operational Qualification (OQ) .............................. 56
`4.8 Handover and Process Optimization ..................... 58
`4.9 Performance Qualification (PQ) ............................. 59
`4.10 Process Validation (PV) ......................................... 60
`4.11 Cleaning Validation ................................................ 61
`4.12 Computer System Validation ................................. 68
`4.13 Analytical Methods Validation ................................ 71
`4.14 Change Control and Revalidation .......................... 71
`
`5. Primary Production ............................................. 75
`5.1 Reaction ................................................................. 75
`5.2 Key Unit Operations ............................................... 85
`5.3 Production Methods and Considerations .............. 96
`5.4 Principles for Layout of Bulk Production
`Facilities .................................................................. 100
`5.5 Good Manufacturing Practice for BPC .................. 109
`
`6. Secondary Pharmaceutical Production ............ 111
`6.1 Products and Processes ........................................ 111
`6.2 Principles of Layout and Building Design .............. 154
`6.3 The Operating Environment ................................... 159
`6.4 Containment Issues ............................................... 176
`6.5 Packaging Operations ............................................ 177
`6.6 Warehousing and Materials Handling .................... 188
`6.7 Automated Production Systems ............................ 190
`6.8 Advanced Packaging Technologies ...................... 192
`
`7. Safety, Health and Environment (SHE) ............. 202
`7.1
`Introduction ............................................................. 202
`7.2 SHE Management .................................................. 202
`
`IPR2020-00770
`United Therapeutics EX2020
`Page 4 of 71
`
`

`

`7.3 Systems Approach to SHE .................................... 207
`7.4
`Inherent SHE .......................................................... 209
`7.5 Risk Assessment .................................................... 211
`7.6 Pharmaceutical Industry SHE Hazards ................. 236
`7.7 Safety, Health and Environment Legislation ......... 257
`
`8. Design of Utilities and Services ......................... 260
`8.1
`Introduction ............................................................. 260
`8.2 Objectives ............................................................... 261
`8.3 Current Good Manufacturing Practice ................... 262
`8.4 Design .................................................................... 263
`8.5 Utility and Service System Design ......................... 270
`8.6 Sizing of Systems for Batch Production ................ 287
`8.7 Solids Transfer ....................................................... 289
`8.8 Cleaning Systems .................................................. 289
`8.9 Effluent Treatment and Waste Minimization .......... 291
`8.10 General Engineering Practice Requirements ......... 297
`8.11 Installation .............................................................. 299
`8.12 In-House Versus Contractors ................................ 300
`8.13 Planned and Preventive Maintenance ................... 301
`8.14 The Future? ............................................................ 302
`
`9. Laboratory Design .............................................. 304
`9.1
`Introduction ............................................................. 304
`9.2 Planning a Laboratory ............................................ 307
`9.3 Furniture Design ..................................................... 321
`9.4 Fume Cupboards ................................................... 329
`9.5 Extraction Hoods .................................................... 336
`9.6 Utility Services ........................................................ 337
`9.7 Fume Extraction ..................................................... 337
`9.8 Air Flow Systems ................................................... 340
`9.9 Safety and Containment ........................................ 344
`
`IPR2020-00770
`United Therapeutics EX2020
`Page 5 of 71
`
`

`

`10. Process Development Facilities and Pilot
`Plants ................................................................... 346
`10.1 Introduction ............................................................. 346
`10.2 Primary and Secondary Processing ...................... 347
`10.3 Process Development ............................................ 347
`10.4 Small-Scale Pilot Facilities ..................................... 352
`10.5 Chemical Synthesis Pilot Plants ............................ 361
`10.6 Physical Manipulation Pilot Plants ......................... 368
`10.7 Final Formulation, Filling and Packing Pilot
`Plants ...................................................................... 369
`10.8 Safety, Health and Environmental Reviews .......... 371
`10.9 Dispensaries ........................................................... 371
`10.10 Optimization ........................................................... 371
`10.11 Commissioning and Validation
`Management .......................................................... 371
`
`11. Pilot Manufacturing Facilities for the
`Development and Manufacture of Bio-
`Pharmaceutical Products ................................... 372
`11.1 Introduction ............................................................. 372
`11.2 Regulatory, Design and Operating
`Considerations ....................................................... 373
`11.3 Primary Production ................................................. 388
`11.4 Secondary Production ............................................ 402
`11.5 Design of Facilities and Equipment ....................... 417
`11.6 Process Utilities and Services ................................ 442
`
`Index ........................................................................... 447
`
`IPR2020-00770
`United Therapeutics EX2020
`Page 6 of 71
`
`

`

`Primary
`pharmaceutical
`production
`
`ROGER SHILLITOE, PHIL MASON and FRED SMITH
`
`This chapter considers the production of the bulk active ingredient or bulk
`pharmaceutical chemical (BPC) that is subsequently converted by physical
`means into thefinal drug’s presentation form.
`This area of the pharmaceutical industry has much in common with fine
`chemical manufacture, The unit operations carned out are similar and many
`fine chemical and speciality chemical manufacturers also manufacture phat-
`maceutical intermediates.
`
`Traditionally, the bulk production was carried out on a different site to the
`R&D and secondary processing. The style of operation, attention to cGMP and
`culture of a primary site, was more associated with the type of chemistry or
`operation carried out.
`Three main influences are changing the face of the BPC industry:
`
`regulators, particularly the FDA, are putting greater emphasis on reviewing
`BPC production, and recognize the effect that failure in quality can have on
`the finished dosage form;
`® major pharmaceutical companies are focusing on “Research and Develop-
`ment’ and ‘Marketing and Selling of the finished product’. Secondary
`manufacture to a limited extent, and primary or BPC manufacture to a
`greater extent, is being sub-contracted out to third parties;
`e BPCs are becoming more active and tonnage requirements are dropping as a
`result. Linked with this, the size of the equipment used in the manufactureis
`reducing. The mereased activity also brings increased handling considera-
`tions and limits for exposure, which in turn drives towards closed processing
`operations, which is also consistent with improvements to cGMP.
`
`5.1 Reaction
`The production of the BPC is by three main methods:
`
`e chemical synthesis: Examples of synthetic conversions include aspirin,
`diazepam, ibuprofen. This method produces the largest tonnage;
`
`75
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 7 of 71
`Page 7 of 71
`
`

`

`PHARMACEUTICAL PRODUCTION; AN ENGINEERING GUIDE
`
`« biotechnology or microbial action: Examples include antibiotics, vaccine
`production, blood plasma products. This method produces the high value
`products,
`e extraction: This can be by extraction of natural materials from animal or
`plant material such as the opium alkaloids, dioxin, heparin, msulin (pigs
`pancreas), thyroxine (animal thyroid gland).
`
`This chapter will concentrate on the first two methods. The extraction
`method for naturally occurring materials was the main source ofdrugs up to the
`1930s but was being gradually replaced with synthetic routes to products.
`There is resurgence now in extraction techniques linked to the biotechnology
`area, where specifically developed or altered organisms are allowed to grow and
`produce a desired product that is harvested and extracted. This is discussed in
`Section 5.1.2.
`
`5.1.1 Synthetic chemistry based processes
`Various general synthetic chemical reactions are utilized in the synthesis of
`BPCs. These include simple liquid/liquid reactions, complex liquid reactions
`with catalysis such as Grinards, Freidel Craft, reaction with strong reagents
`such as phosphorous oxychloride, thionyl] chloride or elemental halogens such
`as bromine or chlorine. Gas reactions with liquids are common for example
`with hydrogen, hydrogen chloride or phosgene.
`Most reactions in the pharmaceutical industry are carried out on a batch
`basis, in non steady state operation, Continuous processing is occasionally used
`for a few generic tonnage commodity BPCs or where safety can be improved by
`the benefits continuous processing can bring by inventory minimization.
`
`Conventional batch reactor systems
`The batch reactor is the workhorse of the synthetic BPC industry. Typically
`made from stainless steel or glass lined mild steel, capacities ranges from 500
`litres at the small scale to 16 m* at the large scale. Some processes employ
`reactors of even greater capacity but this is becoming unusual as the activity of
`new drug substances increases.
`The reactoris typically fitted with an externaljacket or halfpipe coils so that
`the temperature ofthe contents can be adjusted. Occasionally ifa high heat duty
`is required, further coils can be placed inside the reactor.
`Typical operating conditions are from —25°C to + 160°C, and full vacuum
`to 6barg, Generally, reactions at elevated pressures above | bar g are uncom-
`mon, with the exception of specific gas reactions such as hydrogenation.
`However, more processes are now being developed where working at an
`
`76
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 8 of 71
`Page 8 of 71
`
`

`

`PRIMARY PHARMACEUTICAL PRODUCTION
`
`elevated pressure brings benefits — for example, it can allow the selection of
`the ideal solvent for a reaction that could not normally be used at the ideal
`reaction temperature because this would be aboveits atmospheric boiling point.
`The temperature is normally adjusted by indirect contact with a heating or
`cooling medium circulating through the coil or jacket, but direct heating with
`live steam or quench cooling with water or other materials is possible. The
`medium used for the heating and cooling fall into two main areas:
`
`® multiple fluids; typically steam, cooling water, refrigerated fluid such as
`ethylene glycol or brine. These are applied in sequenceto the coil orjacket as
`required:
`single fluids: typically some form of heat transfer oil, heated or cooled by
`indirect contact with steam, cooling water or refrigerant, and blended to
`provide the correct fluid to the coil or jacket.
`
`Agitation is provided to the reactor to ensure good heat transfer and good
`mixing for reaction. Depending on the process requirements, various agitation
`regimes can be set up using different agitator profiles, speeds and locations.
`Connections are made to both the top and bottom of the reactor to allow
`material to be charged into the reactor, materia] to be distilled from the reactor,
`and liquids to be drained out.
`Reactors are normallyfitted with a manway to allow entry for maintenance
`purposes. Historically, this was also the way in which solids were added to the
`reactor and samples were extracted, but this practice is becoming less common.
`
`Alternative reactor systems
`Other types of reactor systems exist with each having their own specific
`advantages for specific processes. These include the loop reactor that specia-
`lizes in gas-liquid reactions at elevated pressures, such as hydrogenation, and
`the batch autoclave reactor that specializes in high-pressure reactions of
`100 bar g and higher.
`
`Materials of construction
`Reaction modules can be constructed from other materials dependant on the
`chemistry being employed and requirements for heat transfer. These include
`glass, plastics and exotic metals such as hastelloy or titanium.
`
`5.1.2 Biotechnology based processes
`The processes in biotechnology are based on cultivation of micro-organisms,
`such as bacteria, yeast, fungi or animal and plant cells. During the microbial
`process the micro-organismsgrow the product, whichis either contained within
`
`77
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 9 of 71
`Page 9 of 71
`
`

`

`PHARMACEUTICAL PRODUCTION AN ENGINEERING GUIDE
`
`the cell or excreted into the surrounding liquor. The micro-organisms need
`carbon substrate and nutrient medium for growth and the microbial processis
`normally performed in water.
`There are essentially three steps to biotechnology processing, namely:
`
`« fermentation;
`@ recovery,
`® purification,
`
`The equipment in which the microbial process is carried out is called the
`fermenter and the process in which micro-organisms grow or format productis
`called fermentation.
`Once the product is formed it is recovered from the biomass or the liquor by
`downstream processing, ¢.g., centrifugation, homogenization orultrafiltration.
`Purification of the recovered product
`is
`then required. Two differing
`techniques are required depending on whetherit is for bulk large-scale or for
`small-scale genetically manipulated organisms. Large-scale recovery can be
`likened to bulk chemical organic synthesis operation.
`
`Fermentation
`The fermenter is the equipment used to produce the micro-organisms.
`Biotechnology applications of fermentations divide conveniently between
`microbial types and mammalian cell culture. Microbial fermentation, which
`can encompassvery large-scale antibiotics as well as smaller scale recombinant
`products,
`is characterized by fast growth rates with accompanying heat and
`mass transfer problems, Mammalian cell culture is characterized by low growth
`rates and high sensitivity to operating conditions. Both techniques have
`common design principles.
`Several different types of vessel are used for large-scale microbiological
`processes, and their degree of sophistication in design, construction and
`operation is determined by the sensitivity of the process to the environment
`maintained in the vessel.
`The following is a brief description of the main types of fermenters:
`
`(a) Open tank
`The simplest type of fermenter is an open tank in which the organisms are
`dispersed into nutrient liquid. These have been used successfully in the brewing
`industry. In the anaerobic stage of fermentation, a foam blanket of carbon
`dioxide and yeast develops which effectively prevents access of air to the
`process. Cooling coils can befitted for controlling temperature during fermen-
`tation,
`
`78
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 10 of 71
`Page 10 of 71
`
`

`

`PRIMARY PHARMACEUTICAL PRODUCTION
`
`(b) Stirred tank
`Stirred-tank fermenters are agitated mechanically to maintain homogeneity, to
`attain rapid dispersion and mixing of injected materials, and to enhance heat-
`transfer in temperature control and mass-transfer in dissolving sparingly soluble
`gases such as oxygen. The extent to which these are achieved depends mainly
`on the power dissipated into the medium by the agitator, so that the agitator is
`essentially a power transmission device. The effectiveness of the power input
`depends on the configuration of the agitator and other fermenter components.
`For acrobic fermentations, air is injected through a sparger, a single nozzle
`or a perforated tube arrangement, positioned well below the lowest impeller to
`avoid swamping it with gas. The sparger should have provision for drainage so
`that no culture medium remainsin it after the vessel is discharged.
`Therate ofair supply must be sufficientto satisfy the oxygen demandof the
`fermentation after allowing for the efficiency of oxygen dissolution achieved.
`Instead of a rotating stirrer, some systems obtain the mechanical power input
`by using a pumpto circulate liquid medium from the fermenter vessel through a
`gas entrainer and then back into the fermenter. This separates the liquid
`movement and gas dissolution functions into separate specialized units. Two
`designs have evolved using this principle — the ‘loop’ fermenter and the “deep
`jet’ fermenter. In the loop fermenter, the gas dissolution device is a subsidiary
`vessel into which gas is mjected, and the gas-saturated liquid is recirculated to
`the main growth stage. In the deep-jet system, gas is entrained into a high-
`powerjet of liquid injected into the liquid in the fermenter, re-entraining gas
`from the vessel headspace. Exhaust gas is purged partly from the vessel
`headspace and partly from the specially designed circulation pump, from
`which the degassed liquid passes through a supplementary cooler before
`passing to the gas entrainer. This system gives high gas dissolution rate, but
`has correspondingly high power consumption compared to conventional
`systems. The liquid and entrained gascan also be introducedinto the fermenter
`through a “bell’, which holds the gas bubbles in contact with the recirculating
`liquid to enhance gasutilization.
`
`(c) Gas-lift and sparged-tankfermenters
`This design has no mechanicalstirrer and the power required for mixing, heat-
`transfer and gas dissolution, is provided by the movement of gas through the
`liquid medium. The gasis, therefore, the power transmission system from the
`gas compressors into the vessel. While the relatively low efficiency of gas
`compression seems to make this design unattractive,
`it has some important
`advantages compared to the stirred-tank system. Firstly,
`the absence of a
`rotating agitator shaft removes the major contamination risk at its entry point
`
`79
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 11 of 71
`Page 11 of 71
`
`

`

`PHARMACEUTICAL PRODUCTION; AN ENGINEERING GUIDE
`
`to the vessel. Secondly, for very large vessels, the required power input for
`agitation is just too large to be transmitted by a single agitator. Thirdly, the
`evaporation of water vapour into the gas stream makes a small contribution to
`cooling the fermentation. The fermenter interior does, however, need careful
`design to ensure that the movement pattern of the gas through the system
`produces satisfactory agitation.
`The various designs of non-mechanically agitated fermenters can be
`grouped broadly into sparged vessels and gas-lift (including air-lift) fermenters.
`Sparged-tank fermenters are usually of high aspect ratio, with gas introduced at
`the bottom through a single nozzle or a perforated or porous distributor plate.
`The gas bubbles rise through the liquid in the vessel and may be redispersed by
`a succession of horizontal perforated baffle-plates sited at intervals up the
`column. In the gas-lift fermenters, internal liquid circulation in the vessel is
`achieved by sparging only part ofthe vessel with gas. The sparged volume has a
`lower effective density than the bubble-free volume, and the difference in
`hydrostatic pressure between the two sections drives the liquid circulation
`upwards in the sparged section and, after gas disentrainment, downwardsin the
`bubble-free section. The two sections may be separated by a vertical draught-
`tube.
`
`Important design considerations for good fermenter operation
`The following are important design considerations in fermenter operation:
`(a) Aeration and agitation
`Animal cells are shear-sensitive (mild agitation is therefore required) and they
`are often sensitive to air bubbles. These considerations impose significant
`constraints on oxygen transfer design. One way m which this problem has been
`addressed is by the use of gas exchange impellers. Another strategy is to
`circulate medium through the reactor while simultaneously oxygenatingit in an
`external loop. A third methodis to use silicon tubing through whichair diffuses
`into the liquid medium.
`Cell culture medium often contains serum, which has a tendency to cause
`foaming. Since defoamants may inhibit growth, agitation and aeration systems
`must be designed to minimize this potential problem. However, care must be
`taken in the amount of agitation applied because, although it provides good
`oxygen and heat transfer characteristics, it can result in mechanical degradation
`of the cells. Usually systems with gentle agitation also minimize foaming. The
`type of impeller, baffles, and tank dimensions influences the degree of mixing.
`Note that mammalian cell cultures are more easily damaged by these mechan-
`ical forces than microbial cultures.
`
`80
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 12 of 71
`Page 12 of 71
`
`

`

`PRIMARY PHARMACEUTICAL PRODUCTION
`
`(b) pH
`The internal environment of living cells is approximately neutral, yet most
`microbes are relatively insensitive to the external concentrations of hydrogen
`and hydroxyl ions. Many organisms grow well between pH 4 and9, although
`for any particular organismthe required pH range is small and accurate control
`is essential, Note, however, that there are exceptions where growth outside this
`range can occur.
`
`(c) Sterile design
`The importanceofsterile design cannot be over emphasized; even the presence
`of a single contammant will be disastrous. The fermenter must be designed to
`be easily cleanable (smooth surfaces and no crevices), after which it must be
`sterilized. The mosteffective form ofsterilizationis to utilize clean steam to kill
`both the live micro-organisms and their spores. This is usually defined as
`maintaining 121°C for 20 minutes. Shorter times and higher temperatures can
`be used but not vice versa, The quality of the steam supply is important; clean
`steam is required for mammalian cell culture, whereas, plant steam with
`approved additives can be used for large-scale antibiotics.
`Ifthe fermentation design calls for sterility, the following special precautions
`are required:
`® air should be provided by an oil free compressor;
`e Clean in Place (CIP) and Sterilize in Place (SIP) systems should be
`incorporated into the design;
`the fermenter and all associated piping and vessels should be designed to
`allow sterilization initially by 1.5 bar g steam. Branch connections should be
`minimized. All lines should be free draining and have minimum dead legs
`with the correct type of valves specified. Selection of internal surfaces,
`piping design, and valves is critical
`in ensuring effective removal of
`unwanted organisms duringsterilization and preventing subsequent ingress
`of contaminants from outside the sterilized system;
`many fermentation media, at the large scale, can be sterilized continuously
`by heat. Economies can be achieved by incorporating heat
`recovery
`exchangers in the system to preheat the feed;
`e all seals and instruments must be designed to withstand steam sterilization;
`e the equipment should be designed to maintain sterility e.g. to include the use
`of steam seals on agitator inlets, double O-rings for probe imsertion and
`steam blocks on transfer lines:
`piping should be stainless steel;
`® an integrated approach should be taken to the physical layout, the piping and
`instrumentation (P&ID) flowsheeting and the sequencing to ensure that
`sterility is an integral part of the design;
`
`81
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 13 of 71
`Page 13 of 71
`
`

`

`PHARMACEUTICAL PRODUCTION, AN ENGINEERING GUIDE
`
`(d) Temperature control
`The temperature for organism growth ranges from approximately —S°C to
`80°C. However,
`the actual
`temperature is important, particularly for cell
`cultures, so temperature control is critical. The lowerlimit is set by the freezing
`point of water, which is lowered by the contents of the cell. The upper limit
`depends on the effect of temperature on the vital constituents of the organ-
`isms — for example, protein and nucleic acids are destroyed in the temperature
`range 50° to 90°C,
`
`(e) Media sterilization
`Medium ingredients should be controlled through a careful quality assurance
`programme. However, sterilization is also required and there are essentially
`three methods used:
`® continuous sterilization for large scale. The time and temperature of the
`continuous sterilizer should be optimized based on the most heat resistant
`contaminant. The hold section of the continuous sterilizer should be
`designed for plug flow to prevent back mixing;
`e in-situ batch sterilization by heat for smaller batches;
`e sterilization by filtration for heat sensitive products such as cell culture.
`
`Recovery and purification
`The product separation and purification section is critical to the design of a
`fermentation plant; indeed, the bulk of capital and operating costs for a typical
`plant are often connected with this area. The design of product recovery
`systems encompasses both intracellular and extracellular products from both
`mucrobial and mammalian cell fermentation broths:
`
`(a) Large-scale extracellular products
`Technologies for recovering the simpler extracellular products consist of
`conventional unit operations such as vacuum filtration, crystallization, liquid-
`to-liquid extraction, multi-effect evaporation, precipitation and distillation.
`These are similar to the basic organic synthesis processes detailed earlier in
`this section,
`
`(b) Recombinant products
`Recombinant therapeutic products can be intra- or extracellular depending
`upon the host micro-organism. Recovery facilities for the more complex
`intracellular protein products involve cell harvesting, debris removal, pellet
`washing and recovery, product concentration, desalting, purification and sterile
`product finishing operations.
`The recovery and purification of protein products from fermentation broths
`involves rapidly-evolving, state-of-the-art unit operations. The complexity of
`
`82
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 14 of 71
`Page 14 of 71
`
`

`

`PRIMARY PHARMACEUTICAL PRODUCTION
`
`these operations is increased due to the heat and shearsensitivity ofthe proteins
`being recovered.
`
`The use of recombinant-DNA organisms can also affect the design of the
`cell recovery area. If the organismsare notkilled in the fermentationarea, the
`recovery area handling the live organisms must be designed in accordance with
`applicable guidelines for containment.
`Typical methods for recombinant product isolation and purification include:
`
`(a) Cell disruption
`is inside the cells. The
`For intracellular products the product of imterest
`objective of cell disruption is to release this product for further separation.
`Cell disruption is usually carried out by mechanical means. This can be by use
`of homogenizers, grinding by beads or by high pressure liquid jet impacting.
`Other methods are use of sound, pressure changes or temperature changes and
`chemical methods. The separation of product from the cell debris after cell
`disruption is usually done by centrifugation.
`
`(b) Centrifugation
`Centrifuges are commonly used for cell harvesting, debris removal, and pellet
`washing operations. Cells can be separated using disc-stack or scroll decanter
`centrifuges. The latter allows cell washing prior to subsequent processing. The
`arrival of steam sterilizable, contained designs have made the use of such
`machines more suitable.
`
`(c) Ultrafiltration
`Ultrafiltration is widely utilized in the recovery and purification of protein
`products. The main uses of ultrafiltration are as follows: concentrating protein
`products; desalting product solutions by diafiltration; exchanging product
`buffer solutions by diafiltration; and depyrogenating of buffer solutions used
`in the process. Ultrafiltration is also finding increasingly wider use in the cell
`harvesting operation. It has an advantage over centrifugation in this situation
`since it subjects the protein to less heat and shear effects, Ultrafiltration is
`excellent for processes using cell recycle and in particular for mammalian cell
`applications.
`
`(d) Electrodialysis
`Electrodialysis is sometimes used to remove salts, acids and bases from
`fermentation broths. A unit will consist of compartments separated by alternate
`anion and cation exchange membranes. A directelectric current is then passed
`through the stack to effect the separation.
`
`83
`
`IPR2020-00770
`IPR2020-00770
`United Therapeutics EX2020
`United Therapeutics EX2020
`Page 15 of 71
`Page 15 of 71
`
`

`

`PHARMACEUTICAL PRODUCTION: AN ENGINEERING GUIDE
`
`(2) Chromatography
`Chromatography is the main technique for final purification of the product
`protein. Chromatographic separations take various forms depending on the
`driving force for the separation. There are essentially two basic forms of
`chromatography; partition chromatography (such as gel filtration) and absorp-
`tion chromatography (for