Assessing the Risk of Extractables and Leachables on Biopharmaceutical Processes

Single-use (SU) solutions are increasingly adopted in biomanufacturing. The associated risks are manageable, considering that extractables data can be fully elucidated with analytical tools. However, SU solutions still require extensive extractables & leachables (E&L) testing as a crucial part of process validation.  

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For decades, industry and regulatory bodies primarily focused on assessing the potential risk of E&Ls for patient safety and drug quality in container closure systems (CCS). The scope of validation for CCS is usually well-defined due to fixed product design and a specific application. However, the wide range of use cases for single-use systems (SUS) in biopharmaceutical production processes requires more complex E&L evaluations and risk assessment.

As a general requirement for equipment used in the manufacturing of pharmaceuticals, the Code of Federal Regulations (CFR), Title 21, Part 211.65 states: "Equipment shall be constructed so that surfaces that contact components, in-process materials, or drug products shall not be reactive, additive, or absorptive so as to alter the safety, identity, strength, quality, or purity of the drug product." (1)

Biomanufacturing companies face the challenge of finding the best balance between regulatory compliance and appropriate validation expenditure. Thus, the level of effort to validate SUS must consider the risk of the component for the process in its intended use regarding any compounds released by the construction material.

A Closer Look at Extractables & Leachables

Extractables are chemical entities that are extracted from plastic contact materials using laboratory experiments that "may accelerate or exaggerate the normal conditions" (USP <1663>) (Figure 1)(2). Testing involves examination with a selection of different extraction solvents (organic, low pH, and high pH solutions) at elevated temperatures for a prolonged time and using multiple analytical techniques for detection, identification, and quantification.

Leachables are a subset of extractables derived directly from extractables. They become drug impurities by indirectly interfering with formulation constituents like the active pharmaceutical ingredient (API) (Figure 1)(2). Only a compound released from a SUS into a process stream that can survive the downstream processing (i.e., is present in the final drug product) can eventually become a leachable (USP 1664). A leachables study might be omitted if the assessment of the extractables data leads to toxicologically safe exposures (3).

Currently, USP <665> is the only relevant standard describing the extractables testing for polymeric components of SUSs used in drug manufacturing. Extraction solutions defined in the standard are: 50% ethanol, acidic extraction (pH 3) solution, and a basic extraction (pH 10) solution. Sartorius aims to provide its customers with the most comprehensive extractables data; we decided to extend this set of extraction solutions with pure ethanol and pure water. We also developed the Extractables Simulator – a qualified software platform that scales extractables data for Sartorius products and assemblies and predicts the total amount of extractables based on customers' processes.

^{Figure 1 – Relationship Between Extractables, Leachables, and Drug Product Impurities.}

The Importance of Extractables & Leachables Testing

The awareness of E&L testing of plastic components grew in the late 1990s. In a landmark case, compounds leaching from rubber stoppers of prefilled syringes were assumed to be the

cause of pure red cell aplasia (PRCA) in patients with chronic renal failure. As one consequence, the U.S. Food and Drug Administration (FDA) published the guideline "Container Closure Systems for Packaging Human Drugs and Biologics" in 1999. USP <1663> for extractables and USP <1664> for leachables were then released, providing guidelines for determining and assessing E&Ls for CCS.

Generally, the E&L risk to patient safety is significantly lower for SU technology compared to CCS because of larger process volumes, shorter contact times, purification steps, process performance, and proximity to patients (5). The only reported E&L issue for SU devices was the presence of an additive degradant which was detrimental to cell growth, negatively influencing the process performance of a SU bioreactor (6). Nonetheless, E&L testing is mandatory for SU production equipment. It is also necessary to assess the potential impacts of E&Ls on the process. Consequently, USP <665> and USP <1665> describing extractables testing and risk assessment of SU components were released in 2021.

Regulatory authorities require drug product manufacturers to obtain and provide extractables data for the devices used. SU suppliers support their customers by generating and sharing this data. This shared responsibility is fundamental to the "extractables ecosystem" outlined by the Biophorum Operation Group (BPOG), of which Sartorius is an active member.

Biomanufacturers are responsible for performing leachables testing during process validation. SU suppliers, like Sartorius, assist end-users by consulting activities and providing leachables testing services. To complement current FDA guidance on this topic, scientists from the FDA, industry, and academia have been working together since 1999 in the Product Quality Research Institute (PQRI) Leachables and Extractables Working Group to share best practices and propose scientific recommendations based on analytical and safety evaluation thresholds for E&L testing.

Process Risk Assessment

The distance along production stream, exposure temperature, exposure duration, process fluid interaction, and dilution ratio are important factors when assessing the likelihood of process equipment-related leachables.

Subsequently, a risk assessment is performed to define the test scope and the validation strategy. There are several guiding documents like USP <665> or BPOG best practices guide for evaluating leachables risk from polymeric single-use systems describing the potential workflow of such an assessment (7; 8)

A risk assessment should be conducted for each component to evaluate the applicability of the extractable profile data. For components considered to be at high risk to leachables, including those taking up leachables extensively or those stored for longer periods, an assessment of leachable profile studies, including safety concerns, and should be taken into consideration, as necessary.

EU GMP Annex 1.

To determine the process risk, bio manufacturers should consider the following points:

1. What is the likelihood of leachables? The answer should consider the SU equipment and process parameters such as temperature, contact time, process fluid interaction and dilution factor, or materials' characteristics.
2. Are these leachables a patient risk? The distance along the production stream and the drug development stage should be considered: the closer the step to the patient, the higher the risk.

After performing an E&L risk assessment, biopharmaceutical manufacturers can evaluate the effort required to validate a particular SU product or component within the process

No One Size Fits All Validation for Single-Use Systems

There are often uncertainties regarding which extractables and leachables tests are required to validate SUSs appropriately. Carrying out a component-by-component analysis is necessary to meet regulatory expectations and keep processes effective, efficient, and safe.

Explore Sartorius E&L Testing Portfolio

References

^{(1) Academy ECA. (n.d.-a). New USP General Chapters on Extractables and Leachables: <1663>, <1664>. Retrieved July 11, 2022, from https://www.gmp-compliance.org/gmp-news/new-usp-general-chapters-on-extractables-and-leachables-1663-1664}

^{(2) Plastic primary packaging materials | European Medicines Agency. (n.d.-b). Retrieved July 11, 2022, from https://www.ema.europa.eu/en/plastic-primary-packaging-materials}

^{(3) Li, K., Rogers, G., Nashed-Samuel, Y., Lee, H., Mire-Sluis, A., Cherney, B., Forster, R., Yeh, P., & Markovic, I. (2015). Creating a holistic extractables and leachables (E&L) program for biotechnology products. PDA Journal of Pharmaceutical Science and Technology, 69(5), 590–619. https://doi.org/10.5731/pdajpst.2015.01073}

^{(4) Hammond, M., Nunn, H., Rogers, G., Lee, H., Marghitoiu, A. L., Perez, L., Nashed-Samuel, Y., Anderson, C., Vandiver, M., & Kline, S. (2013). Identification of a leachable compound detrimental to cell growth in single-use bioprocess containers. PDA Journal of Pharmaceutical Science and Technology, 67(2), 123–134. https://doi.org/10.5731/pdajpst.2013.00905}

^{(5) Schellekens, H., & Jiskoot, W. (2006). Eprex-associated pure red cell aplasia and leachates. In Nature Biotechnology (Vol. 24, Issue 6, pp. 613–614). https://doi.org/10.1038/nbt0606-613}

^{(6) United State Pharmacopoeia <665> Polymeric Components and Systems Used in in the Manufacturing of Pharmaceutical and Biopharmaceutical Drug Products. (2021). http://www.uspnf.com/notices/comment-period-extended-packaging-general-chapters-appearing-pharmacopeial-forum-43-3}

^{(7) Scott, B., Ullsten, S., Wang, P., Madsen, G. L., Dale, G., & Wong, K. M. (2020). BioPhorum Best Practice Guide For: Extractables Testing of Polymeric Single-Use Components Used in Biopharmaceutical Manufacturing. In BioPhorum Operations Group (BPOG) (Vol. 2).}