Standardized Extractables Testing Protocol for Single-Use Systems in Biomanufacturing Part 2

This article presents a consensus standardized extractables testing protocol for single-use systems in biomanufacturing

This article was originally published in the November – December 2014 issue of Pharmaceutical Engineering® magazine.  Click here for access to Part 1, Part 3, Part 4, and Part 5.  Get part three delivered straight to your inbox by subscribing to iSpeak.

Application of the Extractables Data

The extractables testing information package to be provided by an SUS supplier is not intended to be passed directly to a regulatory agency without a process- and product-specific evaluation. Rather, the purpose of the information package is to allow the SUS end user to rigorously estimate the types and amounts of leachables that will be generated by the SUS component during its intended bioprocessing use in order to assess risks to patient safety and to demonstrate product compatibility, process performance, and fitness of the functional design for its intended purpose.5 ^,6 ^, 7 ^, 8 ^, 9 ^, 10 ^,11 ^,12 ^,13 ^,14 ^,15 ^,16 The use of standardized protocols also provides a baseline which can be used for comparative assessments of SUS from different suppliers as backups or alternate sources. Such an approach greatly facilitates the long-term success of SUS for biopharmaceutical manufacturing.

Note: the final responsibility for confirming the safety and efficacy of a healthcare product remains that of the end user, who should take a science and risk-based approach to determining what additional studies should be conducted based on the application, point and phase of use.

Scope

This BPOG’s standardized extractables testing protocol applies, but is not limited, to the following SUS components that come into contact with product or process fluids. The standardized extractables testing protocol does not cover final container closure systems.

• Bags and films used for storage, mixing, or as bioreactors
• Tubing
• Tubing connectors and disconnectors
• Aseptic connectors and disconnectors
• Sterilizing-grade and process filters
• Tangential flow filtration cassettes
• Sensors
• Valves
• Elastomeric parts (gaskets, O-rings, diaphragms, and septum)
• Wetted polymeric surfaces of positive displacement pumps
• Chromatography columns
• Molded parts of mixers (e.g., impellers)
• Filling needles

A supplier of SUS assemblies is not required to generate extractables data for SUS components not manufactured by them as long as the assembly supplier provides end users with data from the actual manufacturer of the component that complies with the standardized extractables testing protocol.

Extractables Studies

Methods applied in SUS extractables studies are specific to each category of SUS components. One key aspect of extractables testing studies is ensuring that the SUS component is exposed to a volume of solvent sufficient to effectively model what occurs during use of the component in actual biomanufacturing processes. For the majority of components, the ratio of a sample’s surface area to the volume (cm2/mL) of solvent to which it is exposed during testing should be maintained at 6:1 or greater.17 One important exception to this rule involves filters, for which the ratio of effective filtration area to solvent volume (cm2/mL) should be maintained at 1:1 or better. For any other SUS components for which the 6:1 (cm2/mL) surface area to volume ratio (SA/V) standard cannot be achieved, exposure of component surface area to solvent volume ratio should be maximized. In these exceptional cases, the final component surface area to solvent volume ratio arrived at should be justifiable based on the component’s intended use.

When performing extractables testing, the sample extraction setups listed in Table A for the various SUS component types are used. Extraction solvents, exposure times, and exposure temperatures by SUS component type are listed in Table B. The proposed study conditions along with the following instructions should be adhered to as closely as is practical.

• Negative controls to calculate background levels should be included for all tests, using the same test setup minus the test article. For negative control, polytetrafluoroethylene (PTFE) bottles are recommended for inorganic elemental analysis, while validated or qualified clean glass bottles are suitable for organic analysis.
• If an item is pretreated prior to actual use, the item should be pretreated the same way before being used in extractables testing. For example, extractables testing results for a gamma-irradiated component cannot be used to represent the results of the same component after autoclaving.
• If the SUS component is intended for use after gamma irradiation, a gamma-irradiated test article should be used for the extraction study. The test article should be irradiated to attain a minimum dose within 10 kGy of the maximum allowed dose (e.g., 45 to 55 kGy, if the maximum allowed dose is 55 kGy). The irradiation facility (i.e., irradiator design, equipment, and process) used should be validated according to ANSI/AAMI/ISO 11137-1:2006 and ANSI/AAMI/ISO 11137-3:2006. Due to the fact of degassing of volatile organic compounds from the gamma-irradiated components, the time between the gamma irradiation and the extraction test should be five weeks to represent the typical worst-case production scenario.
• If the component is intended for use after autoclaving, an autoclaved test article should be used for extraction study. The test article should be autoclaved according to the component product claim. The time between the autoclaving and the extraction test should be within 24 hours or as soon as practical. If the component can be either gamma-irradiated or autoclaved, separate studies for each condition should be performed.
• At least two samples of a component should be tested for extractables, each from different production lot.
• When recirculation methods are used in extractables testing on filters, inert materials such as PTFE should be used for surfaces of pumps, tubing, and other components of the fluid supply system that contact recirculating fluids.
• During the extraction, part of the test solvent may evaporate. For this reason, the starting and end volume of the test solvent should be recorded. These values may be used in calculations for correction of analytical results, where appropriate.

Acknowledgements

The authors sincerely thank the more than 40 colleagues from 18 companies in the BPOG Extractables Work Group for their contribution in developing our proposal, and in particular the following individuals: Tony White, Director BioPhorum Operations Group; Gerry McAuley, Facilitator BioPhorum Operations Group; Bobbijo V. Redler, Ph.D. Associate Principal Scientist Merck & Co., Inc.; Nancy Sweeney, Senior Scientist MTS Gallus Biopharmaceuticals; Ping Wang, Ph.D. Principal Scientist Johnson & Johnson; Russell Wong, PhD Sr. Manager Manufacturing Sciences – Raw Materials, Bayer Healthcare; Sally A. Kline, Scientific Director Amgen; Cara Weitzsacker, PhD QC Senior Specialist Bayer HealthCare; Amy J. Stitt, M.S. Scientist I Bristol-Myers Squibb; and Robert Repetto, Senior Director External Affairs Pfizer. The authors appreciate the detailed constructive review of the manuscript from Dr. Duncan Low from Amgen and Dr. Dennis Jenke from Baxter. We also thank Terry Hudson from Genentech, Dr. Michael T. Jones from Pfizer for reviewing the article, and Jim Sayer from Amgen for providing useful input on gamma irradiation.

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