Insights Gained into the Identification, Qualification and Utilization of CRO Laboratories in Extractables and Leachables Studies

• Baxter Healthcare Corporation

Introduction: Extractables and Leachables

During their manufacture, storage and use, pharmaceutical drug products come into contact with polymeric materials, components and systems. Although these components and systems are constructed from materials and by processes that seek to minimize the extent to which contact can occur, neither truly inert materials and systems nor truly benign contact conditions exist and interactions which potentially impact product quality can occur. One such interaction is the migration of components out of the material and into the pharmaceutical drug product. Migrating substances are a concern due to their potential impact on the finished drug product’s suitability for use. For example, migratory substances could adversely affect the safety and efficacy of the finished drug product, directly or indirectly. The extent of migration must be evaluated, and it must be established that the impact of the migration is within acceptable values.

To properly assess the risk and manage the hazard posed by migratory substances, their identities and accumulation levels of in the finished drug product must be known. These two pieces of information establish the magnitude of the patient exposure (dose) and the hazard posed by an individual substance. The process by which migrating compounds are discovered, identified and quantified is termed “chemical assessment.”

Essentially, the chemical assessment process can be performed in one or two ways, via extractables testing or leachables testing. In extractables testing, the test article is the material, component or system itself. The test article is extracted in a solvent and the solvent is analytically characterized for extracted substances. In leachables testing, the finished drug product itself is tested, after contacting the material, component or system, for substances that were leached from the material, component or system. In either case, the intent of the analysis process is to discover, identify and quantify all extracted or leached substances that are present in the sample above an established threshold amount. Extractables testing establishes the potential for an interaction to occur, while leachables testing establishes the magnitude of the interaction that did occur.

More detailed discussions of extractables and leachables testing can be found in various general references on this topic (1-3).

Figure 1. Four Steps for Identifying, Qualifying and Implementing a CRO to Perform E&L Studies. This four-step process represents a systematic approach for identifying, qualifying and implementing a CRO that effectively augments the expertise and meets the needs of the contracting organization.

Collection, interpretation, and utilization of extractables or leachables (E&L) data are not trivial processes and the scientific and practical requirements for performing these activities may extend beyond the technical and/or resource capacities of many organizations that are required to possess such data. To bridge these knowledge and resource gaps, organizations turn to contract research organizations (CROs) to provide the necessary expertise, necessary capacity, or both.

As extractables and/or leachables assessments can be extensive and expensive, a high level of diligence must be exercised in identifying, qualifying and utilizing a CRO to perform E&L studies (see reference 4). The relatively large number of CROs claiming to have E&L capabilities simplifies the identification of potential CRO partners but complicates qualifying the right CRO partner. Understanding the nature of the service that the user seeks from the CRO and performing a rigorous and in-depth qualification of the CRO are key success factors in establishing an effective and efficient user-supplier partnership.

The purpose of this two-part manuscript series is to describe the various services that a seeker of E&L support may require, and to propose a four-step process (Figure 1) by which the right CRO partner can be identified and qualified.

Step 1: Assessing One’s Position in the E&L Experience Spectrum

Perhaps the single most important success factor in identifying and qualifying E&L CROs is a clear understanding of contracting organizations abilities in this discipline. As noted in Figure 2, an organizations' capabilities in E&L assessment can fall anywhere between two extremes, from a novice with little or no E&L expertise to a recognized E&L expert with a wealth of knowledge and experience. Where an organization falls in this experience spectrum defines the essential services that the organization is seeking to procure. An organization with little or no E&L experience may seek to procure the missing expertise to address a capability gap. In this circumstance, issues of capacity, albeit important, are secondary. On the other hand, an organization with extensive E&L experience seeks to procure resources to address a capacity gap; that is, to gain access to a larger resource pool, measured in either manpower or capital assets (instrumentation), or both.

Figure 2. Establishing One’s Position on the E&L Experience Spectrum (Step 1). Before seeking out CROs, it is necessary for an organization to understand its needs. These needs are typically linked to the organization’s own level of E&L expertise. Those organizations not especially experienced or knowledgeable in E&L will typically be looking to a CRO to provide the required experience or knowledge. Such organizations are looking to purchase expertise. Alternatively, organizations with a considerable internal E&L expertise may be looking merely to procure capacity. In some situations, the organization may be looking for both expertise and capacity.

This distinction is significant for two reasons. Firstly, E&L assessments are knowledge- and experience-intensive. The technical aspects of study design are not trivial and they require a firm understanding of polymer science, physical chemistry, analytical chemistry and regulatory science. While the objectives of E&L assessment are clarified in the relevant regulations, such regulations are not sufficiently explicit to provide a roadmap for an E&L study. Because of the diversity in pharmaceutical products and pharmaceutical applications, the regulations provide companies with a certain degree of flexibility in terms of a study’s strategies and tactics, as long as the strategies and tactics fulfill the general expectation of good science. Since the regulations do not provide the details around good science, it becomes the companies’ responsibility to establish and justify the “goodness” of their science. This responsibility can be met two ways: through existing resources or through purchased resources.

Secondly, an organization’s level of expertise defines the level of oversight that it can supply to the E&L study. An E&L novice has little or no choice but play a passive role in the E&L study. The E&L novice relies entirely on the CRO to “get it right,” as the E&L novice has little or no ability to differentiate right from wrong, or useful information from useless information, or strong study design from poor study design, or accurate analyses from “good guesses”. This presents a considerable disadvantage, as the E&L novice bears the full responsibility for the study’s technical quality but lacks the ability to judge, and therefore impact, the study’s technical quality.

In contrast to this relatively powerless situation, the E&L expert enjoys the ability to engage in the E&L study by whatever means and to whatever extent deemed necessary and appropriate. In terms of study design, this means that the E&L expert can consider aspects of the study design which may be unique to his situation and beyond the capabilities of the CRO. In terms of generated data, the E&L expert provides a second pair of eyes in assessing the quality of the analyses performed by the CRO. In this circumstance, the E&L expert has the ability to critically assess the CRO-generated data. Conclusions drawn by the CRO can be “pressure tested” by the E&L expert. Roadblocks to success that are encountered by the CRO can be removed by the E&L expert. Finally, the E&L expert, may, as required, augment the testing performed by the CRO to address a particularly challenging or difficult aspect of the E&L study.

As there are many gradations between novice and expert, one can envision many different working relationships between the contracting organization and the CRO. However, the optimum working relationship cannot be identified and implemented until the contracting organization has established its own ability and desire to actively participate in the CRO’s E&L activity.

Step 2: Identifying and Screening Potential CRO Partners

Identifying Candidate CROs

Once the contracting organization has clarified the specific nature of the services that it requires, the next step is identifying candidate CROs. Given the large number of CROs that advertise their extractables and leachables capability, it is generally simple enough to create a list of potential partners. On the positive side, there are many available “battletested” CROs that combine the proper analytical capabilities with a passion for excellence and a broad-scope, in-depth understanding of the special issues associated with E&L assessment, which they have gained from years of practical experience. Alternatively, there are CROs with expertise that is only in the process of being developed and tested. While such CROs may be appropriate partners, the contracting organization must ask itself whether it wants to provide the CRO with the studies from which it gains experience. Additionally, it may be the case that even the best CROs may be poorly qualified for a specific task. For example, a CRO which has many years experience characterizing inhalation products may not be the best choice for supporting a program that involves a different dosage form (for example, injectables). Finally, all companies seeking CRO support have their own unique circumstances and their own tolerance for risk. Such contracting companies are well-advised to partner with CROs who understand these circumstances and share their tolerance for risk.

Figure 3. Factors to Consider in Screening Potential CRO Partners (Step 2). A larger pool of potential CRO partners should be screened with respect to their essential resources, essential experiences and intangibles so that a smaller number of viable candidates can be identified to move onto the more rigorous vendor qualification process.

Screening Candidate CROs

After a contracting organization has compiled a list of potential CROs, it is necessary to screen this larger list in order to identify which viable CROs should be qualified. For example, Figure 3 illustrates several of the factors that a contracting organization might consider to facilitate the screening process.

Screening for Essential Resources

Perhaps the single most important factors to consider are the essential resources that the CRO has available to support the E&L assessment. These essential resources include a number of items such as essential instrumentation, essential skills, the availability of the resources and the use of secondary suppliers, each of which will be considered in greater detail.

It becomes obvious to a contracting laboratory that extractables and leachables studies require a vast array of both sophisticated and rudimentary instrumentation. It is relatively easy to get lost in the lexicon of the analytical chemist. Nevertheless, it is possible to have some minimum expectations in terms of reasonable analytical capabilities that should be possessed by the CRO. These capabilities include:

• Atomic spectroscopy. Inductively coupled plasma atomic spectroscopy (ICP) is the gold standard for scanning extracts or drug products for their trace elements and metal content, due to its multi-element capabilities, large linear dynamic ranges, high sensitivity and relative freedom from samplerelated interferences. While ICP spectrometers working on the principle of emission of electromagnetic radiation (ICP-AES) have routinely been applied in E&L studies, the utilization of ICPs with mass spectral detectors (ICP-MS) is becoming more common, as such instrumentation has a greater breadth (scans for a larger number of atoms) and provides improved sensitivity over ICP-AES spectrometers.

Occasionally, it is the case that ICP-based procedures will not have the required performance characteristics (e.g., sensitivity, specificity) to characterize specific samples for specific elements. A case in point is measuring mercury in certain samples. Thus, it is appropriate to consider the CRO’s ability to perform such custom analyses.

• Chromatography: the workhorse for discovering, identifying and quantifying organic extractables is chromatography. Given the large chemical diversity of extractables and leachables, as well as the competing objectives of discovery, identification and quantification and the large number of extracting media and drug products that could be subjected to E&L assessment, it is the case that no single chromatographic method can be the sole “go-to” method. Rather, a suite of orthogonal and complementary chromatographic methods is required to fully elucidate an extractables or leachables profile. Such a suite of methods includes:

     . Gas chromatography (GC), with the appropriate means of gas sampling (e.g., headspace,
       purge and trap) for volatile compounds,
     . Gas chromatography with an appropriate means of samples processing (e.g., liquid/liquid
       extraction coupled with evaporative concentration) for volatile and semi-volatile compounds,
     . Liquid chromatography (LC), with sample processing as appropriate (for non-volatile
       compounds) and,
     . Ion chromatography (IC) for ionic compounds.

The above classification considers the mode of separation; however, it is also important to consider the mode of detection. For the same reasons that one would employ multiple chromatographic methods to separate a diverse population of extractables or leachables, one must also employ multiple detection methods that provide the types of information (concentration and identification) required in an E&L assessment. For example, flame ionization detection (FID) is typically employed in GC for analyte quantitation while mass spectrometric detection (MS) is typically employed for analyte identification. Similarly, in LC, spectrometric detection (UV) is typically employed for analyte discovery/quantitation while mass spectrometric detection (MS) is typically employed for analyte identification.

• Supporting analytical methods. It is recommended practice that extracts in extractables studies be analyzed for chemical properties that are indicative of bulk characteristics of the extractables, such as pH, UV absorbance and either total organic carbon (TOC) or non-volatile residue (NVR). The pH establishes whether the extractables are acidic or basic, the UV absorbance establishes certain functional characteristics of the extractables (e.g., whether the extractables are aromatic or aliphatic) and TOC or NVR provide an estimate of the total amount of organic extractables. While such tests do not produce information that can be safety assessed, they provide insights into the total amounts or chemical properties of extractables. A state-of-the-art E&L laboratory should possess these analytical methods.
• Extending analytical methods. In the ideal situation, the spectroscopic and chromatographic screening methods respond to all the extractables and produce definitive identities and concentration estimates for all responses. In reality, this is not always the case and “unknown” extractables (extractables that elude the screening methods) may need to be found, identified and quantified. Doing so may require several analytical tools whose success is situation specific. As an example, so-called “high-end” mass spectrometry (high resolution spectrometers capable of accurate mass determination for establishing empirical formulas or MSn for establishing fragmentation patterns and thus structural building blocks) may be useful in terms of establishing an extractable’s identity. In certain circumstances, more powerful tools, such as nuclear magnetic resonance spectroscopy (NMR) may be required.

In addition to identification, supporting analytical methods may be required for extractable quantitation. Considering LC, not all extractables have the property of strong UV absorbance. Alternate LC detection strategies, such as evaporative light scattering or corona discharge detectors, may be required to produce concentration estimates for extractables that are more or less invisible to the screening methods. Ultimately, the contracting organization must determine whether it is important that the CRO possesses these capabilities.

One simple mistake that a contracting organization can make in the screening phase is to focus solely on the aspect of testing an extract. This is unfortunate, as generating the extract is an important part of the extractables assessment. Generally, the instruments and supplies used in generating extracts are rudimentary when compared with the instrumentation used for analytical testing. Nevertheless, it is appropriate to consider this aspect of the E&L study, because the test articles may present challenges in terms of their extraction. Consider the situation of a filter used in biopharmaceutical manufacturing. Such filters can be very large and cumbersome, which are important factors to consider when designing and implementing an extraction (for example, procuring an extraction vessel). It may be the case that not all CRO candidates have the facilities, hardware and resources to properly extract a contracting organization’s test article.

While it is clear that a CRO must have the required tools to perform E&L assessments, it is equally clear that the CRO should have craftspeople wielding those tools. Another important part of the essential resource screen is performing a skills inventory. While it is somewhat of an over-simplification, successful E&L studies require a number of skill sets, including:

• Skills necessary to properly design E&L studies,
• Skills necessary to properly execute the analytical testing,
• Skills necessary to interpret the analytical results in the context of analytical chemistry (e.g., determine concentrations, elucidate identities), and
• Skills necessary to interpret the analytical results in the context of E&L assessment (e.g., consistency, correlation, and reconciliation of data, reporting of results, establishing the impact of the results).

During the screening activity, the contracting organization should make a reasonable attempt to assess the quality of the CRO’s staff with respect to these very different skill sets. If the contracting laboratory is an expert in the field, then the focus of the assessment is the analytical capabilities of the CRO staff. In assessing the analytical skills of the CRO staff, the contracting laboratory is strongly advised to look past degrees and job titles and focus on the relevant experience, as establishing the relevance of experience may require more than a superficial effort. For example, the type of trace analysis experience that one gains in environmental and geochemical studies is directly relevant to E&L studies. On the other hand, even extensive experience in elucidating protein structures may not be the most relevant credential for a CRO’s lead LC/MS expert to support E&L studies.

If the contracting laboratory is a novice in the field, then it must consider the other skill sets, in addition to analytical capabilities. This can be a challenging task, since as a novice, it may be difficult to differentiate between acceptable and unacceptable credentials. However, since this is a screening exercise and not a more rigorous qualification, the task becomes more simplified. In general, the contracting laboratory should value CROs whose technical staff has a good balance of education and relevant experience.

As important as the breadth of resources are to securing success in E&L studies, “depth” is also an important consideration when screening CRO candidates. Depth, which is measured by a CRO’s ability to assign resources to a given activity, establishes the CRO’s capacity for production output. This capacity for output manifests itself in many ways; for example, it can be the ability to drive an individual study to a timely completion, or the ability to manage multiple simultaneous studies, or the ability to overcome hurdles. As one might anticipate, depth is a consideration for both hardware and human resources and considers both capacity and capabilities.

Depth can be a deceptively-difficult CRO characteristic to establish. One might interpret the depth question in simply numerical terms, such as “how many GC/MS systems do you have?” or, “how many dedicated Ph.D’s are available to my study?” In fact, the depth question has two dimensions: numerical availability and capacity utilization. While it stands to reason that there is a direct relationship between the number of available resources (e.g., GC systems) and the amount of activity those resources can support, numerical depth is of little use to a contracting organization if that depth is already allocated to other endeavors. A more relevant measure of capacity is either capacity utilization (for example, how much of the GC analyst’s time is currently allocated to projects other than the one you need) or capacity available (e.g., how much of the GC analyst’s time is currently available).

A further issue is the consistency or evenness of the depth, as depth in one area is of relatively little use if it is neutralized by the lack of depth an associated area. For example, a CRO that is well staffed in the GC area but has only one ICP/MS operator may be one that experiences bottlenecks when projects require ICP support.

A special case of the resources issue is the CRO’s use of secondary suppliers. This could include the use of multiple laboratory locations by a given CRO, or it could involve the CRO contracting out certain aspects of a study to its own third party. For example, while NMR may be a useful tool in elucidating structures and establishing identities, it is the case that it is a costly and expertise-intensive capability that may not be available to some CROs. Larger, multi-site CROs may house NMR and other high end analytical technologies at one site. Smaller CROs may contract with third parties (other CROs or even academic institutions) for such services. While such arrangements may be effective and appropriate, some contracting organizations may have practical or business reasons to disapprove of such an arrangement. For example, it may be that the contracting organization’s quality systems require all participating sites in an organization be audited (not just the primary site). When dealing with universities, there may be issues related to Good Documentation Practices (GDP) or Good Laboratory Practices (GLP) compliance.

Screening for Essential Experiences

As is evident from the previous discussion, there is considerable value to be derived from partnering with CROs who are experienced in the art of E&L assessment. It can sometimes be challenging to establish what a CRO’s level of essential experience is. One means of establishing a CRO’s level of experience is to look for evidence of four qualities that are direct reflections of experience; specifically:

• Evidence of knowledge of the field,
• Evidence of participation in the field,
• Evidence of experience in similar situations, and
• Evidence of strategic thinking.

Knowledge in the field is assessed by establishing the CRO’s familiarity with relevant regulations and key publications. While this is relatively easy for the expert contracting organization to assess, it can also be somewhat easy for the novice to handle. If a contracting organization leaves an interview with the key technical leaders at a CRO feeling like they were talking to equals (in the case of the expert) or that they learned something useful from the exchange (in the case of the novice), then this is a good foundation for establishing a partnership. On the other hand, the contracting organization might leave this type of meeting feeling like they were doing all the educating (in the case of the expert) or that little was learned (in the case of the novice).

Another aspect to consider is evidence of participation in the field. For example, there may be good reasons to favor those CROs whose staff includes members of and participants in the various professional organizations that are attempting to establish best practices or those standard-setting organizations who are drafting the regulatory guidance of the future. Similarly, one might favor those CROs whose staff includes authors of key publications in the field or invited presenters at the premier conferences or meetings. On one hand, such CROs might have practices and capabilities that they are very confident in. Additionally, such organizations have had their approaches and procedures assessed by experts as part of their participation in these activities. It is difficult to participate in these activities without engaging in discussion of strategies and tactics or without calibrating good practices and sharing insight into experiences. Finally, it may be the case that a contracting laboratory will value and respect a CRO that actively participates in promoting good science and best practices in their own work.

References

1. Compatibility of Pharmaceutical Solutions and Contact Materials: Safety Assessment of Extractables and Leachables for Pharmaceutical Products. D. Jenke. (Wiley, New York, 2009).
2. Leachables and Extractables Handbook: Safety Evaluation, Qualification, and Best Pr actices Applied to Inhalation Drug Products. D.J. Ball, D.L. Norwood, C.L.M. Stults, L.M. Nagao, Eds. (Wiley, New York, 2012).
3. Update on Undertaking Extractables and Leachables Testing. A. Feilden, (Smithers Rapra Technology, London, 2011).
4. Norwood, D.L. Considerations for outsourcing of leachables and extractables testing. Am Pharm Outsourcing, 9(2): 22 – 28 (2008).

Dr. Dennis Jenke is a Baxter Distinguished Scientist with Technology Resources at Baxter Healthcare Corporation. His primary responsibility includes the assessment of material-product compatibility, specifically with respect to leachables, extractables and product-ingredient binding. He has published extensively in the areas of analytical chemistry, environmental science and material-solution compatibility and serves as an expert reviewer for numerous pharmaceutical and analytical journals. He is a member of professional and standard-setting organizations whose charter is to establish best demonstrated practices in the area of material-solution compatibility and is a frequently invited speaker on this subject. He has authored the book “Compatibility of Pharmaceutical Solutions and Contact Materials; Safety Considerations Associated with Extractables and Leachables”.