Cynthia A. Challener is a contributing editor to Pharmaceutical Technology.

Cynthia A. Challener

Chiral  heteroatom-containing compounds have become highly useful reagents for the  enantioselective synthesis of important building blocks and intermediates used  for the preparation of pharmaceutical compounds. Stephen Han, Chris Senanayake,  and other coworkers from the Department of Chemical Research and Development at  Boehringer Ingelheim Pharmaceuticals in Ridgefield, Connecticut, recently  reported on the development of new and more efficient routes to two types of  important sulfur- (1) and phosphorous-based reagents (2).

Need for a new chiral sulfinyl transfer agent

Chiral  sulfinamides are widely used for the synthesis of chiral amine-containing  compounds, and they also serve as useful chiral ligands for catalytic  asymmetric transformations. The number of routes to these useful compounds is  limited, and few methods offer the accessibility for structurally diverse sulfonamides  (1). The researchers reported that their goal was to develop a route for the  synthesis of hindered sulfinamides on a large scale in a practical manner (1).  Previously, the researchers at Boehringer Ingelheim had developed a versatile  method for the preparation of sulfinamides by means of cyclic-oxathiozolidinone-based  chiral sulfinyl transfer agents. Even though this method was used to prepare  many hindered substrates, it suffered from the need to use excess NH

 using a large excess of solid Li metal and anhydrous NH

  and presents both safety and waste generation issues (2-4) Therefore, the group  set out to develop an efficient, cost-effective, and practical method for the  synthesis of hindered sulfinamides (1). 

They  reported that the first step was to replace NH

  with a safer and greener reagent, such as lithium bis(trimethylsilyl)amide  (LHMDS), for the final S-O bond cleavage. In order to do so, they needed to  increase the reactivity of the S-O bond, which meant developing a new template  (1). To investigate the reactivity of the S-O bond, the researchers reported  that various 

-butanesulfinates  were reacted with LHMDS. Not surprisingly, the reactivity correlated well with  the electronegativity of the oxygen, which was related to the basicity of the  leaving group (RO-). Thus, sulfinates derived from phenol, particularly those  bearing electron-withdrawing substituents, reacted very quickly and  quantitatively. Importantly, it was also noted that the reaction proceeded in  an enantioselective manner (1).

Based  on these preliminary studies, the researchers reported that optically pure 

-chlorobenzothiazine 2-oxide was  prepared as a new chiral sulfinyl transfer agent on a large scale (2 kg) in 87%  yield and 99.6:0.4 diastereomeric ratio (d.r.) 

 configuration at sulfur) from the corresponding commercially  available chiral aminophenol, SOCI

Preparation of hindered, enantiopure sulfinamides

The researchers  reported that the reactivity of the transfer agent was first tested by treating  it with 

-butylmagnesium chloride  in tetrahydrofuran (THF) to cleave the S–N bond to generate a  diastereomerically pure, stable, crystalline sulfinate ester, to which was  subsequently added LHMDS to cleave the S-O bond to provide enantiopure 

BSA) in high yield and high enantiomeric excess, even  when the two steps were run at 10 °C and 0 °C, respectively (1). This reaction was also run on a 100-g scale (15 °C and 5 °C). After the  two steps, the reaction mixture was quenched with phosphoric acid to  provide a mixture of the starting chiral aminophenol  and (

BSA. The template was crystallized from water and recovered in 99%  yield while the product was extracted using methylene chloride and obtained in  85% yield and 99.5:0.5 enantiomeric ratio (e.r.) (1).

The researchers reported that the  reaction is applicable to the synthesis of a wide variety of structurally  diverse and sterically hindered alkyl and aryl sulfonamides. In some cases, a  lower temperature was required to maintain the very high enantioselectivty. In  addition, they found that the ester intermediate does not need to be isolated,  and a one-pot process is effective (1). 

Extension to hindered, chiral sufinyl ketimines

Furthermore, in  the same study, the researchers applied the methodology to the preparation of related  sterically hindered chiral sufinyl ketimines, which are key intermediates for  chiral amines and typically prepared from ketones and sulfinamides in the presence  of a Lewis acid. Yields for sterically hindered ketones with this reaction are,  not surprisingly, low. With the new chiral sulfinyl transfer agent, however, the  researchers reported that imine nucleophiles were added to the sulfinate ester  intermediate, making it possible to access hindered products (both alkyl and  aryl) in good yields and high enantiomeric purities (1).

The researchers then investigated  the value of the chiral sufinyl ketimines as substrates for the preparation of  chiral amines. They reported that reduction of the ketimines with NaBH

 in THF proceeded in very high yields with high selectivity (diastereomeric  ratios > 90:10). The sulfinyl group was also found to clearly influence the  selectivity, and the researchers are investigating further the preparation of  different chiral amines under different reaction conditions (1).

Wanted: structurally diverse P-chiral phosphines 

Chiral phosphines are widely recognized as important ligands for asymmetric transition-metal  catalysts and as effective organocatalysts for enantioselective transformations.  The researchers, however, noted that there are few efficient methods for preparing  optically active 

-chiral phosphorous  compounds, and those that are used are generally limited to nonsterically  hindered substrates (5).

Recently, Han and his colleagues at  Boehringer-Ingelheim reported on the successful development and use of MeO–BIBOP,  MeO–BOP, and P-chiral biaryl ligands in a number of important asymmetric  reactions, such as propargylations (6), hydrogenations (7), and Suzuki-Miyaura  couplings (8). The ligands were all prepared from a bulky P-chiral phosphine  oxide that, at the time of their research could only be obtained using a  resolution-based synthetic route. Han, Senanayake, and coworkers, therefore, set  out to develop a general method for the efficient and stereoselective synthesis  of 

-chiral phosphine oxides with diverse  structures and functionalities (5).

Taking a page  from their research notebook on the chiral sulfinyl transfer agent, the researchers focused their efforts on developing a chiral phosphinyl transfer agent based on  the 1,3,2-benzoxazaphosphinine-2-oxide structure (5).

The researchers reported that the challenge was to overcome the low reactivity of P–N  and P–O bonds. This goal was achieved by activating the P–N bond (increasing  its eletrophilicity) with an arylsulfonyl group (specifically a tosyl group) on  the N atom, and activating the P–O bond with a phenol derivative that could act  as an effective leaving group (as was the case with the sulfinyl transfer  reagent). The researchers noted that the design also ensured that the P−N and  P−O bonds have differentiated reactivity toward nucleophilic substitutions, thereby  enabling their sequential cleavage with two different organometallic reagents. They  then described how the desired (

)-1,3,2-benzoxazaphosphinine-2-oxide  derivative was prepared from an intermediate aminophenol-based auxiliary that  was easily synthesized on a large scale from the readily available compound (

)-2-(1-aminoethyl)-4-chlorophenol.  The transfer agent was obtained in high yield 

 addition of 1-methylimidazole  (1-MeIm) to the chlorophenol in dichloromethane with a diastereomeric ratio of  98:2, and was then recrystallized to give the pure isomer. The yield on a 100-g  scale was 85% (5).

Han et al.  reported that the chemoselective cleavage of the P–N bond proceeded upon  treatment with Grignard reagents or 

BuLi  in THF at low temperature (-20 °C) (5). This reaction occurred with inversion  of configuration at phosphorous and generated diasteromerically pure (

-butyl and mesityl derivatives, in moderate  to good yields. When 4 equivalents of the Grignard reagent 2-MeO-PhMgBr were  used, the reaction was complete in 15 minutes at -10 °C (5). The researchers  reported that cleavage of the P–O bond proceeded using a variety of reagents to  generate a wide variety of (

)-chiral  phosphine oxides. While bulky Grignard reagents (

-BuMgCl) reacted  slowly, addition of the corresponding lithium compounds proceeded in good  yields with good enantioselectivity. Primary alkyl and vinyl Grignards were also  effective, as were alkynyl and ferrocenyl lithium reagents. Chiral versions of several Buchwald-type ligands were also effectively prepared. It should also be noted that the free phosphine ligands could be obtained in excellent yield without  erosion of the enantiopurity via reduction with polymethylhydrosiloxane (PMHS)  in the presence of Ti(OiPr)

The researchers  asserted that numerous types of functionality can be incorporated into the  chiral phosphine oxides prepared using this new method, making it possible to  synthesize a wide variety of interesting chiral phosphines for use as ligands  and/or organocatalsyts (5). As an example, the researchers reacted a  vinyl-substituted chiral phosphine oxide with dialkyl- or diarylphosphine−borane  adducts to generate enantiomerically pure bisphosphine compounds in high yield  (5).The new approach was also used  to prepare the bulky P-chiral phosphine oxide from which Boehringer-Ingelheim’s  new P-chiral ligands were derived as earlier described. In this case, a different  (

)-1,3,2-benzoxazaphosphinine-2-oxide  derivative was first prepared by reacting the chiral template with  dichloro(2,6-dimethoxyphenyl)phosphine followed by H

-BuLi to this  compound followed by reaction with MeLi/MgBr

-OEt provided the  desired chiral phosphine oxide with a 98.3:1.7 er. The researchers asserted that this new method is a practical,  stereoselective, and high-yield route to P-chiral phosphine oxides, which are  of interest as intermediates for preparing P-chiral phosphine ligands as well  as applicability for novel chiral ligand structures for asymmetric synthesis (5).

Articles

New routes enable the efficient synthesis of enantiopure sulfinamides and structurally and sterically diverse P-chiral phosphine oxides.

New Chiral Sulfur and Phosphorous Chemistry from Boehringer Ingelheim

Risk  management is always a priority in pharmaceutical manufacturing. With highly  potent drugs, the level of risk management required is even higher. For oral  solid dosage forms based on highly potent APIs, rigorous care must be taken  throughout the production process (granulation, mixing, tableting, etc.) to  ensure the highest level of quality. Shielding operators from exposure to these  highly potent drugs is paramount. Initially, for operator protection, the emphasis  was placed on the use of extensive personal protective equipment (PPE), but  more recently, it has shifted to the use of contained equipment and automation.

Most large  pharmaceutical companies in general are well prepared in terms of providing developmental  and commercial manufacturing capabilities to support their pipelines of highly  potent drugs, according to Clemens Stief,  team leader/PPD development for Pfizer's Freiburg, Germany facility, which is  part of Pfizer  Global Supply (PGS). The requirements for the handling of highly potent drugs  are quite demanding with respect to environmental, health, and safety  considerations, and the necessary investment for appropriate facilities is significant.  Some CMOs, however, have identified the capabilities required for handling  highly potent drugs, and there are a few companies out there offering  containment capabilities, he adds.

With  exposure of operators a real concern, separating them from the drug product is  critical. “The real equipment breakthrough for the manufacture of highly potent  solid dosage drugs in terms of both safety and efficiency has come in the form  of automation,” says Stief. “With automation, it is possible to achieve a 100%  remotely controlled manufacturing facility with no human interaction during the  manufacturing process,” he notes. Stief points to the fully automated solid-dosage  form manufacturing suites used for large-volume products such as smoking  cessation drugs as prime examples.

These  benefits can be harder to realize with smaller-volume products, which are often  oncology drugs. Automated equipment is often not designed for smaller-scale  operation. Thus, it may only be a solution if platform technologies are applied  to a variety of compounds, such as dry granulation followed by capsule-filling  for more than just one product in the portfolio, according to Stief.  Here, of course, the issue of  cross-contamination must then be addressed.

Although  single-use and  disposable systems  have not yet penetrated the solid dosage manufacturing sector to the degree of  their usage in liquid  and aseptic manufacturing, the idea of using disposable parts is promising.  “The use of such systems could allow for a tremendous reduction in cleaning  verification and validation efforts as well as related analytical method  development work. In addition, it could minimize the potential for contamination  of operators and/or the environment,” he observes. 

Although  disposable systems have advantages in certain applications, the CDMO Metrics  elected to install purpose-built, hard-wall isolation technologies in the  dedicated potent and cytotoxic facility it constructed in 2008, according to director of pharmaceutical  development Joe Cobb. “Local ventilation and laminar/down-flow technologies  are versatile and comfortable, but they are quite dependent on work practice.  Similarly, flexible barrier solutions are practical and achieve good  containment, but pose challenges from a cleaning standpoint, or, if disposable,  a cost-of-goods standpoint,” he explains.

With a  limited physical  footprint at its site, Metrics could not house each piece of manufacturing  equipment (granulators, mills, blenders, etc.) in its own customized isolator.  The company thus engineered a series of multi-use, hard-wall isolators that can  accommodate up to three individual pieces of processing equipment, for a total  of eight individual equipment bays. Standard processing equipment was modified  by installing it through a metal baffle, which fits into any bay on any  isolator.  “As a result, we have general-purpose  isolators that can be customized to meet any client request or operation. That  flexibility is very appealing to pharmaceutical companies,” Cobb comments.   

The isolation barriers for its purpose-built  potent facility have performed so well that Metrics has worked closely with its  vendors to design similar isolation barriers for use elsewhere in its  operations in order to provide an extra measure of safety for its employees  even when projects don’t require that level of protection. “We are taking the concepts  of containment that we successfully engineered for our potent facility and  pushing them out elsewhere in development and manufacturing to make those  operations as safe as possible for our operators,” says Cobb.  

Little  has changed over the last couple of years regarding the design principles for containment  facilities, according to Steif, with the leading paradigm being ‘technical  solutions first’ for commercial facilities. “Containment and isolator  technology are the technologies of choice, followed by PPE, laminar-flow booths,  or restricted access barrier systems (RABS), with only some exemptions in  development facilities. This approach means that there is nothing like well-designed  containment for individual pieces of equipment and/or manufacturing suites,” he  asserts. 

Meanwhile, negative-pressure and  respective-pressure cascades continue to be considered the state-of-the-art. Separately,  the shift to smaller batch size is product-related and applies mostly to  oncology drugs with highly selective working principles.

With that key emphasis on  well-designed containment equipment comes the challenge, according to Cobb. “While  the pharmaceutical industry has a good handle on the technology of isolation (Metrics’  hard-wall containment systems are rated down to occupational exposure levels  (OEL) of 30 nanograms per cubic meter of room air), the size and scale of the  equipment needed for commercial production can be an issue. In addition, there  is a real need for containment-related vendors with first-hand knowledge of the  needs and opportunities of the pharmaceutical industry,” asserts Cobb.

When constructing its high-potent  facility, the company had to adapt the technologies of vendors that provided  equipment for the production of dangerous substances, such as biologicals and hazardous  dusty materials. “The onus was on us to seek out vendors who specialized in  containment systems for dangerous substances and encourage them to apply their  knowledge to our needs within pharmaceutical development and formulation. It  would be helpful to have vendors who better understand the pharmaceutical  industry and can present ideas for containment advances to us, instead of the  other way around,” Cobb says.

Manufacturers of highly potent solid dosage drugs are also dealing with the issue of segregation and the need  to comply with stricter regulations introduced by several regulatory  authorities, according to Stief. “Such requirements not only influence the facility  layout and HVAC design, they also trigger activities related to industrial  hygiene and monitoring and have an impact on overall equipment efficiency,  thus, making the containment business even more challenging and expensive.” 

Process  analytical technology (PAT) can definitely make a difference, according to  Stief, because it provides many opportunities for preventing operator exposure  to highly potent drugs and drug products. These techniques are also attractive  because they are mostly noninvasive and support process monitoring without  direct product contact or sampling procedures. He points to the use of Raman analysis  for compound identification, which can be achieved through a polyethylene bag. “Near-infrared  (NIR) methods are also available for online blend uniformity measurement in  blending operations, and NIR assays may eventually even support a real-time release  strategy,” he notes.

Both  Cobb and Stief believe that the flexibility of their highly potent solid dosage  manufacturing facilities provides a real benefit to the industry. “With our custom-engineered,  hard-wall isolators, clients have the flexibility to select only those  capabilities needed for their particular projects,” explains Cobb. He notes  that such flexibility is proving increasingly important as greater numbers of APIs  (active pharmaceutical ingredients) are becoming increasingly more potent. “In  addition, many of the new APIs are more difficult, challenging, and hard to  handle, which means those of us who work with them need to be nimble and  flexible in order to respond appropriately.”

The DevCon Facility (Development  Containment) for Product and Process Development at Pfizer´s Launch Site in  Freiburg, Germany can cover batch sizes from 10 to 150 kg and provides full GMP  compliant services.  This flexibility of  scale is important in the development arena, according to Stief. He adds that  the facility can also be used for the production of launch and commercial  quantities of small volume products. PGS is also currently evaluating investment  in additional laboratory-scale equipment in response to the urgent need to have  GMP-compliant lab-scale equipment in a containment environment to cover the initial  phases of the development cycle, according to Stief.

Risk management guides decisions in facility design and operation for highly potent drugs.

Technology Choices in Highly Potent Solid Dosage Manufacturing

Extractables  and leachables (E&Ls) associated with parenteral drugs present an ongoing challenge  to pharmaceutical manufacturers. Any time new materials are introduced into the  extensive system that comprises parenteral manufacturing, which includes any  and all filters, containers, and transfer tubing, and all components of the  final drug product packaging, there is the potential that unknown leachable  compounds will accumulate in the drug product. Even though leachables are  typically present in minute quantities, some can cause significant problems for  patients. Thus, E&Ls must be identified to the greatest extent necessary or  possible and, if found to be a problem, eliminated or reduced to acceptable  levels. The challenge, however, is clear: they can originate from any material  that comes in contact with a parenteral drug during filtration, purification,  formulation, transfer, filing, packaging, and storage, from a new additive in  tubing or a container seal or a new ingredient in a washing solution used  during syringe manufacture, and therefore can be continually changing.   

Recognition  of the issues posed by E&Ls throughout the supply chain has been one of the  most important advances with respect to managing this challenge, according to Carsten  Worsøe, a principal scientist with Novo Nordisk. “The  challenge is that every change in the composition and processing of a part of a  device or a container-closure system potentially can change the leachable  profile in the drug product. Such changes can be introduced by the supplier of the  device or container-closure system or any number of subsuppliers or converters.  The importance of bringing the changes forward to the pharmaceutical company can’t  be overstated. This information is critical to a drug manufacturer’s ability to  evaluate the risks associated with the change with respect to the leachable  profile of the drug product,” he explains.

Range of recent closure and device advances

The increased awareness in  the supply chain has led to several advances in container-closure system and  device technologies. “In each case, critical experiences with interactions of leachables  with drug products led to the development of alternative technologies that  minimize those interactions, and in turn, these examples have further underscored  the role that participants in the extended supply chain have to play in  managing extractables and leachables,” Worsøe observes.

The introduction of coated stoppers for vial  products is one example of such a recent advance, according to Dennis Jenke, a  distinguished scientist in the Technology Resources Division of Baxter  Healthcare Corporation. These  coatings retard the leaching of substances from the stopper’s base rubber  material. In addition to the use of such barrier films and coatings,  elastomer manufacturers are more closely evaluating the raw materials they use,  including critical raw-material quality properties. “Enhanced controls on raw  materials and the use of quality-by-design principles when manufacturing  elastomers will result in cleaner, new elastomer formulations that should  exhibit both reduced levels of extractables and greater lot-to-lot  consistency,” notes Jennifer Riter, senior director of global analytical  services with West Pharmaceutical Services. “The use of new films and coatings  combined with these approaches will help further minimize extractables coming  from an elastomer used in primary packaging for injectables,” she adds. 

Advances have also been made in the  chemistry of UV-cured adhesives used in device manufacture and the process used  to form the needle channel of prefilled syringes, according to Worsøe. In the  former case, the incomplete curing of the adhesives used to glue device parts  together was leading to the interaction of unreacted acrylic acid with  proteins. The solution to this problem was the optimization of the adhesive  formulations and UV curing parameters to ensure that the amount of unreacted  acrylic acid monomer was minimized, which in turn reduced the leaching of acrylic acid-related leachables.       

For prefilled syringes  (PFS) made of glass, the formation of the needle channel is commonly performed  using a tungsten pin at high temperature (approximately 1200 °C). At this  temperature, according to Worsøe, tungsten can be deposited  on the surface of the glass as elemental/metallic tungsten or as tungstates/oxides. The presence of  these tungsten compounds has been shown to lead to  protein aggregation and oxidation in the PFS over time. Different approaches  have been taken to minimize the deposition of tungsten, including optimization  of the pin composition and design and more frequent replacement of the pins. 

The relatively recent commercialization of “low extractables”  plastics such as cyclic olefin copolymer is another example of the development  of new materials for use in the extended supply chain that are specifically  designed to address the E&L issue, according to Jenke.

To effectively screen for E&Ls, it is  essential to use a number of orthogonal analytical methods, or  those that will complement each other with respect to the detection of  different compound classes, according to Worsøe. Such  analytical methods include high-performance liquid chromatography–ultraviolet  spectroscopy (HPLC–UV), liquid chromatography–mass spectroscopy (LC–MS), gas  chromatography–mass spectroscopy (GC–MS), gas chromatography–headspace–mass  spectroscopy (GC–HS–MS), inductively-coupled plasma-atomic emission  spectroscopy (ICP-OES), inductively coupled plasma mass spectrometry ICP–MS, and ion chromatography (IC). Mass spectroscopy is often  coupled with chromatographic techniques for the identification and accurate  mass detection of organic E&Ls. He adds that recent improvements in gas chromatography time-of-flight  mass spectroscopy (GC–QToF–MS) have enabled this technique to be used as an  important method for the identification of unknown organic E&Ls. “More  recently, liquid chromatography-nuclear magnetic resonance (LC–NMR)  spectroscopy and liquid chromatography-solid-phase  extraction-nuclear magnetic resonance (LC–SPE–NMR) spectroscopy  have been shown to be valuable techniques for identifying unknown organic  E&Ls,” Worsøe  says. 

Many of these latest analytical  techniques used for extractables and leachables determinations are improvements  on current technologies; more modern equipment and electronics offer greater  sensitivity, according to Paul Cummings, laboratory operations manager for West  Pharmaceutical Services. West is implementing ultra-high pressure liquid chromatography (UHPLC), which is a  next-generation HPLC technique that requires less solvent and has higher  sensitivity, so also enables the use of smaller sample quantities. Accelerated  solvent extraction, which is an improvement over the reflux extractions used in  the past, is also providing West with more control over temperature, pressure,  and time, thus yielding more reproducible results.

For Jenke, it is the coupling of high-efficiency  chromatographic techniques with information-rich detectors that continues to be  an interesting area of development for E&L analysis.  He points to the  coupling of UHPLC with high-resolution MS detectors capable of providing accurate  mass information, which enables the determination of the empirical formulas for  otherwise unidentified extractables and leachables as being a noteworthy recent  advancement in E&L test methods.  “This development makes the LC  screening process more broad-scope and information-rich, and thus more  productive," Jenke comments.

Even with such advances in the  resolution and accuracy of analytical techniques, there are concerns that  remain. One of the most important issues, according to Jenke, is the fact that the screening  methods commonly employed for organic extractables (GC and LC) are not 100%  efficient in capturing all E&Ls. “Even if one were to identify all of the  peaks in GC and LC chromatograms, it is possible ̶ and in fact likely ̶ that  there would be extractables that the LC and GC methods did not detect.   The questions then are: ‘How does one know whether such uncaptured extractables  exist?’ and ‘How does one find these uncaptured extractables?’ Scientifically  sound and universally applicable answers to these questions are not currently  available.” 

Large-volume  parenterals (LVP) present additional issues when it comes to E&Ls in  the form of the so-called “'volume challenge.'” “The main  challenge for LVPs is the need to develop scientifically based toxicological  acceptance criteria for E&Ls that can be met using currently available  analytical techniques,” Worsøe  notes. With LVPs, such as a dialysis bag used by patients with kidney failure,  the daily volume of the parenteral drug that is consumed can be several liters  compared to injection volumes for a small-volume parenteral (SVP) down to 100  µL. 

If both an SVP and LVP each contain 0.1 mg/L (0.1 ppm) of a leachable  compound, and the two drugs are dosed at 0.05 L and 1 L per day, respectively, the  patient would be exposed to 0.1 mg/L x 0.05 L = 0.005 mg in the case of the SVP  and 0.1 mg/L x 1 L = 0.1 mg in the case of the LVP.  “Thus,” says Jenke,  “all things being equal, leachables would need to be measured in LVPs to much  lower levels than SVPs in order to establish the same degree of safety.”    

In fact, the ‘volume challenge’ can result in a detection limit for the same leachable that is 10,000 times  lower for an LVP compared to that for an SVP, according to Worsøe. “Because it is often the case that such low detection levels cannot be  achieved using existing analytical methods, the approach must be taken to  accept the level that is as low as practically possible,” he concludes.  Although such an approach is a practical  necessity, Jenke notes that adopting this approach increases the uncertainty of  a toxicological safety assessment based on the chemical data. It is appropriate  to address this uncertainty with alternate or additional testing. For example,  if a leachable in an LVP drug product cannot be measured down to a  toxicologically safe level, then it might be possible and appropriate to  measure the same compound as an extractable by extracting the test system with  an extraction medium that is more analytically viable than the drug product. 

Understanding the supply-chain challenge and coupling high-efficiency chromatographic techniques with information-rich detectors are leading to improvements in the management of extractables and leachables in parenteral drugs.

Experts from Novo Nordisk, Baxter Discuss Technological Advances in Addressing the Challenge of Extractables and Leachables

Plants, like human and animal cells,  are capable of producing complex and folded proteins, and plant-based protein  expression technology may provide advantages over cell-culture systems. Bio-Manguinhos/Fiocruz,  the  technical scientific unit of the Oswaldo Cruz Foundation (Fiocruz), which produces  and develops immunobiologicals for public health needs, primarily in support of  programs run by the Brazilian Ministry of Health, is taking plant-based  expression technology to the next level. It recently signed an agreement with  GE Healthcare for the design of a new plant-based multipurpose  biopharmaceutical and vaccine manufacturing facility using a plant-based  expression and production platform from iBio, a developer of such systems.

Plant-based  protein expression is not new technology. The first human test of a therapeutic protein made in plants was conducted by NeoRx  Corp. in 1997, according to Robert Erwin, president  of iBio. The experimental cancer  therapeutic Avicidin incorporated a monoclonal antibody produced in transgenic  plants by a unit of Monsanto. Although there were no problems with the quality  of the plant-made antibody itself, the Avicidin product was not ultimately  commercialized. About the same time, Planet Biotechnology tested a transgenic  plant-derived antibody for the prevention of tooth decay in collaboration with  Guy’s Hospital in London. 

Transgenic  plants have since been used to produce several products that have entered human clinical trials, including gastric lipase, interferon, and insulin.  Plant-produced human glucocerebrosidase, produced in transgenic carrot cells by  the biopharmaceutical company Protalix BioTherapeutics, received FDA approval. In  May 2012, Protalix and its partner received FDA approval for Elelyso (taliglucerase alfa), a plant  cell-produced glucocerebrosidase enzyme  replacement therapy (ERT) for the long-term treatment of adult patients with  Type 1 Gaucer disease. Protalix is also developing an oral form of glucocerebrosidase; Elelyso is parenterally delivered. Viral  vectors were used to produce proteins for individualized treatment of  non-Hodgkin’s lymphoma in a Phase I clinical trial conducted in 2002 (1), and Icon  Genetics is currently conducting a Phase I clinical trial of individualized  cancer therapy based on its transient expression technology for producing  proteins in plants. 

Compared to the traditional use of animal cells grown in bioreactors, plant-based protein expression systems have  several advantages, according to Erwin. Because they do not require the time-consuming  identification and isolation of high-producing cell clones that need to be  scaled up for manufacture, plant-based systems can be operational in much less  time. In addition, the plants are grown in a soil-free, hydroponic medium under  strict climatic and lighting controls for the highest degrees of  reproducibility (see  Figure 

). As a positive consequence, no animal-derived  products or growth factors are used, thereby eliminating the risk of the  introduction of human pathogens into the manufacturing process. Thus, the  expensive aseptic liquid-handling process steps for cell culture are not  required.  

The iBioLaunch technology from iBio  is a third-generation plant-based protein expression platform that uses unmodified  green plants. The first-generation system, which some companies still use, relies on transgenic (i.e., genetically modified organisms)  plants, a process that is slow and relatively  low in yield. Second-generation systems, also still used by some companies, are based on the transient virus-delivery of genes into nontransgenic plants. Although this  technology works rapidly, there are yield constraints and target product-size limitations that restrict its applicability, according to Erwin.

“Harnessing  the combined biological features of bacterial, viral, and plant biology to  achieve the speed of transient production without the yield and size  limitations of older technology, iBioLaunch technology has the advantages of  speed, simplicity, flexibility, and lower cost,” Erwin asserts. He says that unlike  more conventional systems that fundamentally alter a host cell’s DNA, there is  no need to isolate and expand rare, high-producing cell clones to production  level. A gene of interest can be cloned  and inserted into the iBioLaunch vectors and be ready for production at scale  within a month’s time. In addition, the transient nature of the expression system  allows the accumulation of massive amounts of desired protein over a four- to seven-day period, after which time purification can begin.

“The  simplicity of the iBioLaunch system comes from the use of whole plants for the  manufacture of proteins,” explains Erwin. “These plants can be grown in  chemically defined media in the open air or climatically controlled greenhouses  and do not require the expensive aseptic-culture systems required to prevent  contamination of cell-culture production methods. Furthermore, the system is  highly flexible, thereby allowing the expression of vaccine antigens,  monoclonal antibodies, replacement enzymes, blood-cell growth factors, and many  other products that cannot be produced by more traditional expression systems,”  he adds. Other important benefits include the ability to produce proteins  that are difficult to obtain using other methods and the ability to scale-up capacity  readily, for example, in developing treatments for pandemic disease. Also, using whole plants to provide the biomass for manufacturing  obviates the need for bioreactors and media and also reduces development times  associated with traditional cell-culture manufacturing.

Erwin notes that various proteins  have been successfully produced with iBio’s platform, including antibodies,  interferons and cytokines, growth factors, protease inhibitors, clotting  factors, and enzymes for replacement therapy (specifically alpha-galactosidase  A). In addition, a variety of antigens for vaccines against diseases, such as  influenza, anthrax, malaria, yellow fever, sleeping sickness, plague, and human  papilloma virus have been produced, as well as several therapeutic antibodies  for the treatment of acute influenza and anthrax infections. “Virtually any  protein that can be produced in prokaryotic or other eukaryotic expression  systems can be made in plants with the iBioLaunch platform with significant  cost advantages,” Erwin states.

The iBioLaunch technology was validated through the construction of a cGMP pilot manufacturing  facility in Newark,  Delaware that has provided clinical-trial  material for multiple FDA-approved studies, according to Erwin. Human testing  of products made using the iBioLaunch platform began in 2010 with the  initiation of Phase I clinical trials of an H5 avian influenza vaccine  sponsored by the Bill & Melinda Gates Foundation and a vaccine for H1N1  influenza sponsored by the US 

Defense  Advanced Research Projects Agency

,  the results of which were published in 2012 (2). 

Bio-Manguinhos/Fiocruz is interested  in and investing in the iBio plant-based technology." “ "In order to  accomplish our mission and to meet the Brazilian Ministry of Health’s demands,  we are constantly investing in innovative technologies,” says Artur Couto,  director of Bio-Manguinhos/Fiocruz. “The agreement with GE Healthcare is  important because it will allow us to build a new facility based on a very  innovative platform and address an important need of the Brazilian Ministry of  Health,” he says. 

Bio-Manguinhos/Fiocruz  also  has an additional co-development agreement with iBio and its research and  development collaborator Fraunhofer USA Center for Molecular Biotechnology  (FCMB), which will continue to play a key role in advancing iBioLaunch,  according to Erwin. The contract with Bio-Manguinhos/Fiocruz  in Brazil for the design of a new plant-based biomanufacturing facility is the  first for the global alliance between GE Healthcare and iBio, which was  announced in 2012. The agreement with Bio-Manguinhos/Fiocruz and GE Healthcare  for the new plant-based production facility was announced in April 2013.

Although  the details of the process and facility design are confidential, a typical  plant would be based on the following approach. The front-end of the process  would involve technology proprietary to iBio, including the production of green-plant  biomass using hydroponic systems, the transfer of appropriate recombinant  protein expression vectors into the plants, and the extraction of protein from  the biomass (See Figure 

). Downstream operations,  including separation and purification of the target protein and final product  formulation, could be based on the proprietary products and expertise of GE  Healthcare.

, 105 (29), 10131–10136 (2008). 
  2. J. A. Chichester et al., 

GE Healthcare's partnerships with iBio and Brazil's Bio-Manguinhos/Fiocruz for a new plant-based multipurpose biopharmaceutical and vaccine manufacturing facility move plant-based protein production to the next level.

GE Healthcare, iBio, and Bio-Manguinhos/Fiocruz Advance Large-Scale Plant-Based Protein Production

For pharmaceutical manufacturers, finding the cause of product-quality failures and ensuring product quality are  crucial, and various methods can be used. Industrial X-ray imaging is used in  the pharmaceutical industry in a variety of ways, from product-integrity and  materials-distribution analysis to improving product-delivery methods and the  integrity of packaging.  It is also used to address manufacturing  challenges that may occur in the hardware and machinery of a pharmaceutical  manufacturing plant. In short, industrial X-ray imaging can be used to provide  an inside perspective of a product or the mechanisms used to produce that  product.  

  There are two primary modes of  industrial X-ray imaging.  The first is two-dimensional (2D) digital  radiography, which involves capturing static or in-motion "real-time"  images of the inside of an object (or living organism) by passing X-rays  through that product and capturing them on a digital detector.  “This technique  is often used for the simple detection of foreign materials and contaminants in  a product. It is also effective for investigating the distribution of materials  within a delivery device, such as looking at a drug inside of a syringe, or the  active ingredients and excipients in a solid dosage form,” says Jeffrey Diehm, comanaging director of Avonix Imaging, a provider of industrial  X-ray and computed tomography (CT) imaging services and systems. 

The  second, more advanced X-ray imaging technology used in the pharmaceutical  industry is three-dimensional (3D) computed tomography imaging.  With this  method, the same X-ray imaging technology that is used for 2D imaging is also used,  except that instead of capturing a single static image, the sample is rotated 360  degrees while capturing a series of images. These images are then  "reconstructed" into a true three-dimensional representation of the  internal and external features of the sample.  “This imaging method is  quite valuable because it provides the only means for capturing the internal  geometric data of a sample as well as the density distribution within,” asserts  Brian Ruether, Diehm’s business partner and resident technical expert. 

The most common uses for X-ray  imaging in the pharmaceutical industry include process and design verification,  product-quality analysis, foreign-material determination (metal, glass,  organics), fill-level confirmation, and missing-components detection. These  analyses are applied to the various types of solid and semisolid dosage forms,  including tablets, capsules, and gel caps. Packaging materials–from medicine  bottles to syringes–can also be evaluated using digital X-ray and computed  tomography.

One  of the main advantages of X-ray imaging is that it is a nondestructive  analytical technique. Its depth of penetration and reasonably high resolution are  also critical aspects of the technology that make it very useful for  pharmaceutical analysis. There are no other methods that can define the internal  geometry of an object or provide a true three-dimensional view of a finished  product in a nondestructive manner, according to Ruether. In  addition, he points out that X-ray imaging offers high internal and external dimensional accuracy and the ability  to distinguish between materials of varying densities within a sample while  also being fast and cost-effective. 

X-ray imaging can be used to  determine the thickness of layers in multilayer tablets and the shape and size  of the interface between layers, investigate the microstructure of  fast-dissolving tablets and the features of embossed markings on tablet  surfaces, evaluate the morphology and pore-size distribution of granules, and  identify defects in compacted tablets.

In  addition, as long as the materials that comprise individual pills and capsules generate  sufficient X-ray contrast, high-resolution  computed tomography can be used to determine the distribution of the ingredients  (APIs and/or excipients) throughout the pill or capsule by segmenting the components  by size and/or density (see 

 1). The higher energy of the X-rays enables them to readily penetrate most  pharmaceutically relevant excipients and APIs. In addition, with the short-wavelength  radiation, it is possible to get high-resolution images with minimal  diffraction.

The  information available from such an analysis can be used for several purposes.  Comparative evaluation of the internal structures of two supposedly branded  tablets using X-ray imaging can, for example, be used to identify counterfeit  products without damaging the questionable tablets. Changes in the structure of  solid and semisolid drug products over time (i.e., during storage) or under  different stresses can also be identified using X-ray imaging.

Even  the performance of manufacturing processes can be evaluated, and potential  sources of product-quality inconsistencies identified. In one case, a  pharmaceutical company observed that a drug product produced at different  manufacturing sites exhibited inconsistent efficacy depending on the production  location, according to Diehm. To determine the cause of the variation, X-ray  imaging was used to evaluate the level of crystallinity of the interior of tablets  manufactured at each site because the API was crystalline while the binder was  not. “Using high-resolution CT scans, we were able to  determine that there was a significant quantifiable difference in the makeup of  the pills coming from the different plants.  This information was used by  the manufacturer to modify the manufacturing process and achieve a higher level  of consistency between plants,” he explains. 

Improving  delivery and packaging systems

X-ray inspection in pharmaceutical  manufacturing can also be used to simultaneously inspect products for multiple  quality control issues, which safeguards the integrity of the drug product and  brand while ensuring regulatory compliance, according to Diehm. In addition to  formulated dose analysis, X-ray imaging can be used to detect product defects ranging  from insufficient fill levels to damaged seals to misshapen containers to  missing components (See 

 2). “We  have worked with pharmaceutical clients to identify the sources of  inconsistencies in their manufacturing processes and help them validate process  improvements in order to ensure that the products being produced meet the  stringent requirements of the industry,” he comments.   

For  one pharmaceutical company, Avonix Imaging used X-ray  analysis to identify the cause of inconsistencies in the delivery performance  of their syringes. Variation in the syringe- manufacturing process was  resulting in patients not receiving  the prescribed dosage of liquid in the right amount of time. “By analyzing CT  scans of the syringes, it was determined that there was not only a difference  in the inside diameter of the needle but, more importantly, there was also an  inconsistency in the shape of the syringe opening, which sometimes resulted in the  formation of a small burr or ridge that led to the inconsistency in the flow  rate,” Diehm says. With this information, the company was able to modify the  manufacturing process and eliminate these issues.

Even minor flaws in basic product packaging can cause  real problems for drug manufactures and their customers. In many cases, X-ray  imaging can help identify these defects as well. Diehm offers a case in point from a liquid antacid manufacturer that was having a problem with the sealing  of one of its bottles, which benefited from the technique. In this example, the  defective seals were leading to leakage once the  bottles were opened for the first time.  Avonix Imaging scanned numerous  bottles made using different plastic molds and found variation in the wall  thickness of the bottle at the top surface.  “This thickness variation made  it difficult to properly seal the bottle unless enough force was applied, which  was often difficult for elderly patients in particular. Here again, using the  dimensional information provided by the CT scans, it was possible to identify  the source of the problem. As a result, the manufacturer changed the problem  molds and gained more control over its process.”

Recent advances in X-ray imaging  technology have included new, higher-resolution X-ray tube and imaging detector  combinations, along with stronger computing platforms, which enable the imaging  of smaller internal features.  In addition, advanced 3D  analysis software can now provide automated void and particle-density  distribution calculations from the CT data, according to Ruether.

Currently,  the one major limitation of X-ray imaging is that it is not ideally suited yet  for in-line analysis, particularly for certain features of interest. “The  technology is constantly evolving, though,” stresses Ruether. “Higher-resolution and  higher-speed detectors, in combination with advancements, in software analysis  will help overcome the issues that are limiting the use of X-ray  analysis in production environments.”

Additionally,  education will encourage further adoption of X-ray imaging technology. “Our  main goal is to help educate the pharmaceutical industry about how Xray and CT  imaging can be used as a tool for overcoming the challenges that drug  manufacturers face every day,” Diehm says.  “As they learn more and see  first-hand how they can improve the quality and consistency of their products  through the use of X-ray imaging technology, they begin to think of other  manufacturing challenges that might be better addressed through the use of this  nondestructive method," he observes. 

Greater sophistication in 3D X-ray imaging technology raises its utility for QA/QC in manufacturing.

Addressing Manufacturing Challenges with Nondestructive X-Ray Imaging

In the second half of the 2000s, Fujifilm was extending its  business interests outside its traditional camera and digital products. The  company already had a strong presence in medical diagnostics, and felt that many  of the proprietary technologies cultivated in these businesses could be used in  pharmaceuticals, according to Steve Bagshaw, managing director of Fujifilm  Diosynth Biotechnologies, UK.  Thus, in 2008, the company created a  Pharmaceutical Products Division that includes a growing portfolio of companies,  such as Toyama Chemical Company and Fujifilm Kyowa Kirin.

Fujifilm Diosynth Biotechnologies is another  part of the Pharmaceutical Products Division. It was formed following the  acquisition by Fujifilm of the Merck Biomanufacturing Network.  Merck had created the Biomanufacturing  Network following its acquisition of the former Avecia Biologics in February  2010, which it partnered with the former Diosynth Biotechnologies (previously owned  by Schering Plough).

The company consists of sites in both the UK  and the US, which according to Bagshaw, have complementary technologies and facilities and work closely  together to share ideas, services, and expertise in order to benefit their customers.  “While separate business units with individual leaders, the business is  marketed as a single entity with a shared sales team, and the key R&D and quality  functions are also unified under single leaders,” he notes.  The decision on where a customer’s product is  developed and manufactured depends on a number of variables, including  geography, technical fit, and capacity. 

When Fujifilm acquired Fujifilm Diosynth  Biotechnologies, the stated intent of the company was to become a leading global  biologics CMO. “Our two former companies were recognized as world leaders in the  development and manufacture of microbial-based biopharmaceuticals, but had somewhat  limited capabilities and capacity in mammalian-derived products. To meet  growing market demand, over the last two years we therefore upgraded our sites  in both the US and UK,” Bagshaw explains.
  

Specifically,  cGMP mammalian facilities at its Research Triangle Park, North Carolina site were  expanded with the addition of a 1000-L single-use bioreactor (see 

) that complemented the firm’s existing  2000-L stainless steel bioreactor and process-development capabilities at that  site. At its Billingham, UK  site, Fujifilm  Diosynth expanded its  mammalian capabilities with a new cell line and process/analytical development  services and established a dedicated team of 30 people in this area.  The latest high-throughput technologies are used  to enable the rapid transition of biologics from discovery to clinic, according  to Bagshaw.

In addition, a dedicated mammalian cell-culture  manufacturing facility at the company’s Billingham site is currently under  construction and due for completion in the fourth quarter of this year.  This facility will primarily use single-use  technologies, including a 1000-L single-use bioreactor; a second 2000-L  bioreactor is also already planned for 2014. Furthermore, Fujifilm  Diosynth’s Cell Banking Facility  opened in May 2013 and is working on its first customer programs.  
  

The company has not neglected its long-established  microbial-based business either. Over the last two years, it has upgraded a  number of development and pilot-scale laboratories at its Billingham site, with  the installation of new equipment, including eight 

 sterilizable 20 L Sartorius Stedim Biotech fermenters and a  number of fully instrumentable DASGIP parallel bench-top high throughput units.  The R&D teams at both the UK and US sites have also been significantly  increased over the last 12 months.
  

Finally, both sites have seen upgrades in  their analytical development laboratories, with the installation of new  equipment (see 

), including ultra  performance liquid chromatography (UPLC), capillary  electrophoresis-sodium dodecyl sulfate (CESDS), and imaged isoelectric focusing (IEF) instruments that  deliver rapid results in support of the cGMP manufacture of customer drug  products or as a stand-alone service, according to Bagshaw.

Taking advantage of single-use technologies

Much of the new capabilities that Fujifilm Diosynth  Biotechnologies has installed incorporate single-use technologies. “Our  decision to invest in single-use technologies and equipment at the two facilities  was based on three factors: compliance, flexibility and speed,” Bagshaw  observes. He points to the fact that single-use technologies are much more  compatible in a multi-product facility because the risk of cross-contamination  is much reduced, no matter how potent the product. Much reduced cleaning times  also allow the company to offer a much faster turnaround between customer  campaigns, and simplified materials and waste management are further benefits.  
 

 “In addition, a new facility using single-use  technologies can be on the ground in a much shorter timeframe than a  traditional stainless steel facility. The new facility at the Billingham site is  taking less than 18 months from ground-breaking to validation, which can be compared  to the 2-5 years that is required for a stainless steel facility,” says Bagshaw.  The same is true for capacity expansion to  meet customer demands.

To reach its goal of becoming a leader in the biologics CMO  industry, Fujifilm Diosynth Biotechnologies has extended its enhancement activities  beyond its own facilities. Most notably, it recently formed a key alliance with  Piramal Healthcare UK Ltd. “This partnership focuses specifically on the  contract development and manufacture of antibody drug conjugates (ADCs), a  growing niche in biopharmaceuticals. It brings together the expertise of  Fujifilm Diosynth’s biologics development and manufacturing with Piramal’s  world-leading experience in ADC, offering customers a ‘one-stop-shop’ approach,  thereby reducing complexities in the supply chain and vendor management  relationships and leading to shorter time to clinic,” Bagshaw says.  
  

Fujifilm  Diosynth has already received substantial interest in this alliance and is in  discussions with a number of customers for the development and manufacture of ADCs.  The company is also exploring other opportunities. “We are always looking for  ways to enhance our offering to meet customer needs, either by adding  facilities ourselves, or working with third parties,” Bagshaw comments.  In fact, the firm is currently in discussion  with two companies regarding potential alliances, but he is not in a position  to provide details at this time.

Since its inception in 2011, Fujifilm Diosynth Biotechnologies has added capabilities and single-use production capacity for mammalian-derived product manufacturing, upgraded development and pilot-scale microbial laboratories, and installed advanced analytical instrumentation.