Pharmaceutical Development Process Research Articles

Identification and Control of Impurities for Drug Substance Development using LC/MS and GC/MS

Identification and control of impurities for drug substances is a critical task in pharmaceutical process development for quality and safety. The most commonly used analytical technique for impurity analysis in drug substances and drug products is undoubtedly a chromatographic method, namely high performance liquid chromatography (HPLC). Impurity profiling is typically performed by HPLC and impurities are further tested for identification and confirmation by other techniques. Several case studies are presented in this paper to report the identification of unknown impurities employing chromatographic techniques interfaced with mass spectrometry. The task of unknown identification was facilitated by complementary methodologies including tandem mass spectrometry (MS/MS), high resolution mass spectrometry (HRMS), preparative HPLC and NMR. Upon identification of the impurity, the impurity formation was monitored and controlled throughout the synthesis. Three case studies are described where unknown process impurities were analyzed for identification using LC/MS and GC/MS methodologies. It is demonstrated that identification of the unknown impurity enabled chemists to pinpoint the chemical step of impurity generation, aiding the effort to reduce or even eliminate the impurity in the drug substances.

Evaluation of a critical process parameter: Oxygen limitation during cultivation has a fully reversible effect on gene expression of Bordetella pertussis

Modern (bio)pharmaceutical process development requires thorough investigation of all process parameters that are critical to product quality. The impact of a disturbance of such a parameter during processing needs to be known so that a rational decision can be made about the release of the product. In cultivation processes the dissolved oxygen (DO) concentration is generally accepted as being a critical parameter. In this article the impact of a 90 min period of oxygen limitation during the cultivation of the strictly aerobic Bordetella pertussis bacterium is investigated. The cultivation is the most important process step for the manufacturing of a vaccine against whooping cough disease. Samples were taken immediately before and after oxygen limitation and at the end of cultivation of four oxygen limited and three control cultivations. DNA microarray analysis of the full transcriptome of the B. pertussis bacterium revealed that a 90 min period of oxygen limitation has a substantial effect on overall gene expression patterns. In total 104 genes were identified as a significant hit at any of the sample points, of which 58 were directly related to oxygen limitation. The other genes were mainly affected towards the end of cultivation. Of all genes involved in oxygen limitation none were identified to show a significant difference between the oxygen limited and control cultivations at the end of the batch. This indicates a fully reversible effect of oxygen limitation on gene expression. This finding has implications for the risk assessment of dissolved oxygen concentration as a critical process parameter.

PQLI Definition of Criticality

This paper describes progress made by the Criticality Task Team within the ISPE PQLI initiative. It aims to provide a concise, coherent, and universal approach for determining criticality for parameters, material attributes, conditions, and quality attributes. The work also clarifies the risk based distinctions governing the assignment of criticality to provide consistency and facilitate the adoption and implementation of Quality by Design (QbD) principles in the development of pharmaceutical manufacturing processes. The application of the concept of criticality presented in this paper aligns with the principles of ICH Q8, Q9 and Q10 guidelines.

ABC of Bayesian Approaches to Drug Development

In the past several decades, the process of pharmaceutical development has been criticized for not being able to bring promising and safe compounds to the marketplace in a timely fashion. The use of adaptive trial designs could greatly improve the efficiency of drug development. However, adaptive trial design is not synonymous with the Bayesian approach, and the latter has great potential to create separate and further improvement. Here we present a comparative review of frequentist and Bayesian approaches. The comparisons are made using three different perspectives: (i) learning mechanisms; (ii) evidence assessment; and (iii) trial design, data analysis and interpretation of results. Suggestions for planning Bayesian trials are outlined. The Bayesian and classic frequentist approaches are also discussed from a regulatory perspective.

Best Practices for Extractables and Leachables in Orally Inhaled and Nasal Drug Products: An Overview of the PQRI Recommendations

The Product Quality Research Institute Leachables and Extractables Working Group includes pharmaceutical development scientists representing industry, government, and academia. The Working Group was created and constituted to address scientific and regulatory questions concerning the pharmaceutical development process for Orally Inhaled and Nasal Drug Products (OINDP) related to organic extractables and leachables. This effort has resulted in the creation of a detailed "Recommendation Document", which was submitted to the U.S. FDA for consideration in September 2006. The recommendations include proposed safety and analytical thresholds for leachables and extractables, as well as detailed "best practice" recommendations for various aspects of the OINDP pharmaceutical development process, including: materials selection for OINDP container closure system components, Controlled Extraction Studies, Leachables Studies, and Routine Extractables Testing. The Working Group's processes and the detailed and comprehensive recommendations that resulted from those processes, demonstrate that the Product Quality Research Institute collaborative process can result in consensus science-based and data driven recommendations that could have a positive effect on patient care. It is anticipated that the Working Group's recommendations will also contribute to the new "Quality by Design" pharmaceutical development paradigm. This commentary summarizes the best practice recommendations within the context of an overall pharmaceutical development process.

An Integrated High-Throughput Screening Approach for Purification of Solid Organic Compounds by Trituration and Crystallization in Solvents

Trituration and crystallization are essential techniques for purification of intermediates and drug substances in pharmaceutical process development. Traditionally, identifying the optimal solvent conditions for impurity rejection adopts an empirical approach that can be a time and material consuming process. On the basis of thermodynamic considerations for optimizing the purity and the yield of the crystal product, it is necessary to conduct screening experiments with the crude product in different solvents including mixtures of solvents. In this report, we describe the development and the implementation of a high-throughput screening workflow in a 96-well array format for identifying the optimal purification conditions. The impure samples were first triturated at room temperature and subsequently subjected to a thermal cycle in 96 unique solvents or solvent mixtures at a volume of 0.6 mL per well. The compound solubility and the impurity profiles of both supernatant and recovered solid were analyzed by HPLC. Using a mixture of acetylsalicylic acid containing salicylic acid as the impurity, we investigated the effects of material loading per sample and impurity level on product purity/solubility under both screening and scale-up conditions and evaluated the thermodynamic behavior of product−impurity−solvent interactions based on an isothermal ternary phase diagram. During a further case study, a binary solvent system was identified, and the synergistic effect of binary components was demonstrated for purification of an Amgen compound containing three impurities. This high-throughput screening approach is valuable as an integrated part of process development to identify the thermodynamically favored solvent conditions for purification of pharmaceutical compounds.

Normal phase and reverse phase HPLC-UV-MS analysis of process impurities for rapamycin analog ABT-578: Application to active pharmaceutical ingredient process development

ABT-578, an active pharmaceutical ingredient (API), is a semi-synthetic tetrazole derivative of the fermented polyene macrolide rapamycin. Reverse phase (RP)-HPLC-UV-MS and normal phase (NP)-HPLC-UV-MS methods employing an LC/MSD trap with electrospray ionization (ESI) have been developed to track and map all significant impurities from the synthetic process. Trace-level tracking of key impurities occurring at various process points was achieved using complimentary methodologies, including a stability indicating reverse phase HPLC method capable of separating at least 25 starting materials and process-related impurities from the API (YMC-Pack Phenyl column, UV-MS, 210 nm) and a targeted reverse phase HPLC method capable of separating very polar compounds from crude reaction mixtures (Phenomenex Synergi Polar RP column, UV, 265 nm). In addition, a normal phase HPLC method condition with post-column modifier infusion is described for the separation of epimeric impurities, and analysis of aqueous-sensitive reactive species (YMC-Pack SIL column, UV-MS, 278 nm). Process control strategies were established with these combinations of analytical technologies for impurities analyses to enable a rich understanding of the ABT-578 process.

A Cross-Atlantic Dialog on Experimental Use and Research Tools

In Merck KGaA v. Integra LifeSciences I Ltd., the U.S. Supreme Court adopted a broad construction of the regulatory approval exception to patent law infringement, 35 U.S.C. § 271(e)(1), for experiments conducted at early stages of the pharmaceutical development process. But the Court refused to determine whether that exception applies to patented 'research tools,' and failed to address the relationship of that exception to the historic experimental use exception. The U.S. Court of Appeals for the Federal Circuit has narrowly construed the experimental use exception, but also refused in its recent decision on remand in Merck to resolve these questions, leaving in place substantial disagreements over the nature and scope of the exceptions that were reflected in its earlier decision (which the Supreme Court reversed). In contrast to the substantial uncertainties in American patent law, European experimental and regulatory approval exceptions may be subject to somewhat fewer interpretive uncertainties, particularly in light of decisions such as the U.K. Monsanto and German Klinische Versuche (Clinical Trials) cases. But the nature and scope of the European exceptions nevertheless may be subject to dispute and may vary significantly among jurisdictions based on national legislative decisions to limit or extend patent protection, such as the recent Belgian law adopting an experimental use exception that expressly applies to patented research tools. Determining the proper scope and application of experimental use and regulatory approval exceptions remains a pressing concern. These exceptions assure that patent laws intended to provide incentives for technological innovation do not unduly restrict scientific research, innovative medical product development and generic product competition. The social harms that can result from narrow exceptions have been emphasized by the Merck decision, by the recent (initial) invalidation of restrictively licensed stem-cell patents, and by empirical studies that suggest that valid patents may (in light of the narrow construction that has been given to the experimental use exception in the U.S.) increasingly delay or restrict scientific research. However, the scope of these exceptions remains highly controversial, particularly for biotechnological research tool inventions for which capital investments and market returns may depend upon the ability to prevent such unlicensed research uses.In this article, we provide a comparative analysis of the history and current state of the experimental use and regulatory approval exceptions under U.S. and European laws. We explore the application of these exceptions to research tools in academic and commercial sectors, distinguishing research on an invention from research with it, discussing potential differences of treatment among the exclusive patent rights, and noting the arguments for extending or restricting the exceptions. We also discuss relevant constitutional and international treaty-law considerations for legislative and judicial policymaking. We conclude with a dialog that seeks to provide guidance for lawmakers, by identifying relevant questions that will need to be answered in order to resolve the appropriate scope of experimental use and regulatory approval exemptions.

Development of Safety Qualification Thresholds and Their Use in Orally Inhaled and Nasal Drug Product Evaluation

Safety thresholds for chemical impurities and leachables in consumer products such as foods and drugs have helped to ensure public health while establishing scientifically sound limits for identification and risk assessment of these compounds. The Product Quality Research Institute (PQRI) Leachables and Extractables Working Group, a collaboration of chemists and toxicologists from the U.S. Food and Drug Administration (FDA), industry, and academia, has developed safety thresholds for leachables and extractables in orally inhaled and nasal drug products (OINDP), for application in United States pharmaceutical submissions. The PQRI safety concern threshold (SCT) is 0.15 microg/day, and the qualification threshold is 5 microg/day. OINDP are important in the treatment of lung diseases such as asthma and chronic bronchitis, as well as systemic diseases such as diabetes. Analysis of extractables and minimization of leachables in OINDP are vital to ensuring the quality and safety of the final product. It is expected that the thresholds developed by the PQRI Leachables and Extractables Working Group will be used by both industry and regulators to ensure and assess such quality and safety in OINDP applications. In this article, we describe the importance of the PQRI safety thresholds in the OINDP pharmaceutical development process; the background and context of safety thresholds for consumer products; how these safety thresholds were developed using well-established, robust databases and quantitative risk assessment approaches; and how these thresholds can be applied in a pharmaceutical safety qualification process, including FDA regulatory perspectives on the use of safety thresholds for OINDP.

Can pharmaceutical process development become high tech?

Can pharmaceutical process development become high tech?

Understanding critical material properties for solid dosage form design

What is the role of standardized methods for determining the impact of material properties in pharmaceutical formulation and process development? In this Perspective article, we identify material properties that are potentially important in solid dosage form design, and we review approaches linking these properties to product specifications in dry granulation process development. We also assess the potential benefits that could be obtained by standardizing the methods for determining the impact of material properties of commonly used excipients and propose a program of research to achieve the desired goal of an efficient, science-based approach for incorporating material properties in solid dosage form design.

The Routine Collation of Health Outcomes Data from Hospital Treated Subjects in the Health Outcomes Data Repository (HODaR): Descriptive Analysis from the First 20,000 Subjects

Objectives Health technology assessment requires data covering many different facets of treatment. A new resource, the Health Outcomes Data Repository (HODaR), is described and evaluated for its use in the pharmaceutical research and development process. Methods Data were collated for subjects treated at Cardiff and Vale National Health Service (NHS) Hospitals Trust, United Kingdom. Inpatients are surveyed 6 weeks postdischarge by postal survey, whilst outpatients are handed a survey pack when they attend. Survey data cover sociodemographics, resource use, production losses, and quality of life. Electronic hospital data are available for all responders, and linked with survey returns. Sample characteristics, coverage of disease areas, and a more detailed description of data values for diabetes are described. Results Survey responses relating to 16,188 admissions and 4476 outpatient attendances were available relating to around 2000 different diagnoses. Over 5000 pharmacy items and 400,000 biochemistry test results were available. Analysis of utility data showed a broad coverage of diseases. For patients with diabetes the pattern of EQ-5D scores across subgroups is not clear. Health service resource use showed a linear relationship with respect to number of comorbidities. Conclusions HODaR represents a new approach to accessing patient data, and gathers both routine and survey-based data. Although linking survey data to routine hospital systems is a complex task, which produces some limitations, it can produce health outcomes data at relatively low cost. Its performance within the pharmaceutical research and development process needs to be further evaluated in order to assess its most appropriate role.

A Pharmaceutical Biotechnology Virtual Laboratory

Objectives. To develop a software application for the pharmaceutical biotechnology drug research and development process. The Pharmaceutical Biotechnology Virtual Laboratory was offered as a hybrid course in spring 2003. We evaluated (1) the software's pedagogical effectiveness, and (2) how students utilized the software in the teaching/learning process. Methods. Software development involved software-authoring tool selection, mock-up layouts of content screens, educational content creation, and storyboard development with artwork, animation, and programming. All modules were developed and refined based on student usability testing. Course implementation permitted student choice of face-to-face, hybrid, or online course formats. Student learning was assessed through quizzes, pretests, and posttests; assessment of student mode of learning (eg, how the students used the software and course participation format); and transference of learning from the course to other situations. Results. Results of student po...

Liquid chromatography–mass spectrometry using the hydrogen/deuterium exchange reaction as a tool for impurity identification in pharmaceutical process development

HPLC-MS employing deuterium oxide and common MS-compatible deuterated additives in the mobile phase with electrospray ionization is shown to be a viable approach for the structural elucidation of impurities in pharmaceutically active agents following initial studies with protic mobile phases. This approach incorporates the hydrogen/deuterium (H/D) exchange reaction where deuterium is substituted for hydrogen at labile sites. Some developmental compounds studied include an amide, amine, lipopeptide, indole and methyl sulfone. H/D exchange is rapid and the chromatographic performance using deuterated mobile phases is comparable to protic counterparts.

Pharmaceutical Applications of Liquid Chromatography Coupled with Mass Spectrometry (LC/MS)

High performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) is an extremely powerful and indispensable methodology practiced in virtually every stage of pharmaceutical discovery and development processes, including biological target discovery, biological assay for high throughput screening, characterization of physicochemical properties of drug candidates, and drug metabolism and pharmacokinetics. With continued advances and innovations in the areas of column technologies, LC/MS interfaces, and instrumentation, the field of LC/MS is strengthening and expanding to new disciplines constantly. In this report, the recent developments in the LC/MS interface ionization techniques, such as ESI, APCI, APPI, and MALDI, and novel hardware and software of mass spectrometry devices, are compared and reviewed in the light of drug discovery and development effort. The diverse qualitative and quantitative applications of LC/MS in the pharmaceutical industry are reported in four key fields; synthetic organic chemistry, combinatorial library parallel synthesis, bioanalysis in support of ADME, and proteomics. Other analytical techniques used in conjunction with LC/MS to augment analytical information content are also discussed. As the use of LC/MS is exceedingly widespread and ever increasing, this paper primarily focuses on recent progresses reported in the literature with selected publications.

Practical Applications of Monolithic Columns to Pharmaceutical Process Development

High performance liquid chromatography (HPLC) is among the most widely used analytical techniques in the process development of drug substances. With the goal of reducing analysis time, there has been considerable focus on high‐speed HPLC separations. Recently, commercially available monolithic columns have proven to be one of the most promising developments in the area of fast chromatographic separations. In this work, pressure drop, column efficiency, and retention behavior of monolithic columns (Chromolith type) were evaluated and compared with those of conventional columns packed with porous stationary‐phase particles. It was demonstrated that high‐speed HPLC separations could be achieved with monolithic columns at acceptable pressure drops without significantly compromising column efficiency. The applications of monolithic columns in pharmaceutical process development, such as reaction monitoring, column fraction screening, and analysis of mother liquors and unstable analytes, are described with respect to the quality of separations, as well as, enhanced throughput and speed of analysis. It is concluded that the use of monolithic columns offers a significant advancement over currently available techniques in the high‐speed and high‐throughput analysis of pharmaceutical compounds. Some practical aspects in utilizing monolithic columns for fast separations are also discussed.

Practical aspects of fast HPLC separations for pharmaceutical process development using monolithic columns

A large number of samples can be generated during pharmaceutical process development. Fast separation for these samples is usually challenging due to the complexity of sample matrix, which requires high efficiency as well as high speed. Monolithic columns (E. Merck, Germany) were investigated as a possible tool for reducing separation time in reversed-phase HPLC without significantly sacrificing efficiency or resolution. Both van Deemter plots and separations of alkyl benzenes and in-process samples showed that monolithic columns were suitable for fast separations without significantly compromising resolution. Practical parameters including the pressure drop, retention factor, selectivity, and tailing factor of monolithic columns (Chromolith type) were compared to those of conventional YMC 150 mm × 4.6 mm (3-μm particles) and 250 mm × 4.6 mm (5-μm particles) packed columns. The batch-to-batch reproducibility of the 100 mm × 4.6 mm Chromolith columns from five randomly ordered batches was also compared to the 250 mm × 4.6 mm YMC particle-packed columns. Fast and efficient separations of complicated process samples including crude drug substances, reaction mixtures, and crystallized mother liquors were demonstrated for both monolithic columns and conventional packed columns. The analysis times were decreased by three to seven times on the coupled monolithic columns, while maintaining the comparable resolution to typical 5-μm particle-packed 250 mm × 4.6 mm columns.

Example of Finishing Technologies as Key Elements for Successful Active Pharmaceutical Ingredient Process Development

Little has been published so far to emphasize the role of finishing technologies (crystallization, filtration, drying) as crucial elements for successful process development of active pharmaceutical ingredients (APIs). In the presented example high marketing forecasts stressed the objective for the process to be robust, simple, and tailor-made for high-volume production. The major hurdle was the purification of the reaction mixture of an intermediate containing inorganic salts, polymers, isomers, and colored byproducts that needed to be separated. Systematic application of finishing technologies paved the way to a commercial process. Removal of colored byproducts and isomers was found to be the most challenging task after separation of inorganic salts by quench and of polymers by charcoal treatment. The problem was resolved in three steps. First, solvent screening for the crystallization yielded toluene to be most efficient to separate colored byproducts. Second, solubility measurements of product and isomers provided an operating range of the process parameters for an economic crystallization at an unusually high concentration (60% w/w). Isomers could be separated since they remain soluble at endpoint temperature. To avoid the problem of wall crusts during scale-up, the metastable range was estimated experimentally. And third, near-infrared spectroscopy was implemented as an on-line measurement method for the product concentration in toluene to determine the endpoint of evaporation and thus to facilitate robustness and yield optimization. As further result of proper elaboration of crystallization conditions the crystals exhibited compact cubic morphology and large size. Consequently, filtration and washing of the wet product cake were efficient, and the drying process could be eliminated before continuing with the next synthesis step.

Chromatography as an Enabling Technology in Pharmaceutical Process Development: Expedited Multikilogram Preparation of a Candidate HIV Protease Inhibitor

Chromatography plays a vital role in supporting preclinical pharmaceutical development, whether in providing assays for purity determinations, preparative separation of small amounts of intermediates for route selection studies, or purification of bulk drug substances on multikilogram scale. All three approaches are illustrated in the recent development of a candidate HIV protease inhibitor in these laboratories. Chiral supercritical fluid chromatography (SFC) on the hundreds-of-milligrams scale afforded an enantiopure intermediate to facilitate early synthetic studies, HPLC on the tens-of-grams scale provided purified material for use in salt form investigations, and HPLC using a 30 cm column was used to purify 5.6 kg of a key intermediate to provide material for early preclinical evaluations.

Application of high throughput technologies to drug substance and drug product development

This presentation describes the application of novel high throughput physical–chemical technologies to the pharmaceutical discovery and development process. The rationale for such platforms is described in light of the changes that have occurred in the biological and chemical processes leading to drug target evaluation and lead identification. Several high throughput platforms are described for identification and evaluation of solid forms and formulations of drug candidates including salt, hydrate and solvate selection and polymorph discovery and evaluation. The application to the development of oral and intravenous formulations for animal model and human clinical evaluation is also discussed. The importance of informatics to design experiments and capture and analyze data is highlighted. Examples are described showing the power of high throughput systems to discover knowledge that enables pharmaceutical scientists to make more informed and better decisions about product development choices.