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Industry experts provide insights on the challenges and importance of using buffers in downstream processing.
Buffers are used in a variety of biopharmaceutical processes including isolation and purification during protein capture, polishing, filtration, as well as chromatographic, reaction, and crystallization steps. Madhavan Buddha, senior scientific manager at Biocon Research Limited, estimates that the volume of buffer used per year exceeds 2000 kL. According to Kimo Sanderson, vice-president of marketing and client services at Asahi Kasei Bioprocess America, between 1-10 kL of buffers per batch are required for typical clinical or commercial-scale biopharmaceutical manufacturing. “Each process requires a specialized buffer composition that can be made in a traditional way by batch compounding with manual testing or, in many cases, with innovative, continuous compounding equipment known as inline buffer dilution, which formulates, monitors, and delivers buffers from concentrates,” says Sanderson.
The use of buffers is especially important in downstream processes to protect proteins from variations in pH, according to Michiel E. Ultee, PhD, principal of Ulteemit BioConsulting. “Buffers serve to protect the protein from changes in pH by buffering or absorbing changes in pH. A well-buffered solution will maintain its pH in spite of variations in processing, containers, and raw materials. Proteins are sensitive to changes in pH, which can lead to denaturation, aggregation, and fragmentation,” says Ultee.
Buffer precision and accuracy may enhance recovery and yield of the target proteins, which may decrease manufacturing costs. “The need to discard or adjust out-of-specification buffers goes down while processing efficiency increases. More importantly, high-quality buffers help ensure maximum recovery of biological products,” says Sanderson.
The choice of buffer is essential depending on how robust or streamlined one wishes their process to be, according to Nandu Deorkar, PhD, vice-president of Research and Development at Avantor Performance Materials. “The choice is between inorganic buffers, including phosphates, on the one hand, or organic buffers, such as Tris or MOPS [(3-(N-morpholino)propanesulfonic acid)], on the other hand, as these offer different levels of pH and conductivity control and impact other downstream process steps differently,” says Deorkar.
BioPharm International spoke with Buddha, Deorkar, Sanderson, and Ultee to get their insights on the challenges involved in using buffers in downstream processing.
Buffer challenges in downstream processingBioPharm: What are the challenges that need to be addressed when using buffers in downstream processing processes? How can these challenges be overcome?
Deorkar (Avantor): One major challenge that presents itself when using a large quantity of buffers is that any contaminant in the buffer can have a detrimental impact on filtration. All of the buffer must be filtered before one puts it in the downstream process, so if the buffer contains, for example, some insoluble matter that is not part of the specification--that can pose a problem. And if a requirement is to filter a larger volume but there isn’t the necessary filter surface area, the filter can clog.
Another challenge is meeting consistency and quality requirements for the buffer, since not all buffers in downstream processing are necessarily required to be GMP-quality. The solution is to use a reputable supplier that guarantees consistency and has a GMP quality system with procedures in place to ensure quality in their manufacturing processes, and the capability to test and manufacture high-purity grade material.
There are several things one must keep in mind when selecting a buffer. In addition to making sure that the buffer is compatible with the drug product and the process one is using, one must ensure it is compatible with the production facility and the intended method of environmental disposition, and that it is easy to handle in terms of health and safety.
A key item here is to use a buffer that has a higher buffer capacity so small changes in the process do not lead to pH shift. Using a buffer with higher buffer capacity provides for a more robust process without requiring large quantities of buffers. It’s important that the buffer that is used meets the impurity criteria for material that can interact with the protein product or the chromatographic resin. These can include heavy metal impurities, some of the color components that come in a buffer, or even plant-derived material such as citric acid. Some of these can cause a problem in the chromatography column one uses.
Make sure that the buffer has the required consistency and specifications for a particular product. We have seen issues caused by potential impurities. For example, depending on the manufacturing process, some buffers can contain ppm levels of iron. If there is no specification addressing iron content, that iron may discolor the chromatographic resin.
Sanderson (Asahi Kasei): The traditional method of buffer production consists of batch compounding with manual testing. This approach requires time-consuming post-run quality control analysis to ensure accuracy. Since the resulting buffers reside in large tanks, cleaning and validation costs accumulate while crowded manufacturing facilities and pilot plants lose valuable floor space.
The changing landscape of the biopharmaceutical industry poses an additional challenge. As the blockbuster drug paradigm shifts toward orphan drugs and biosimilars, lower-volume manufacturing operations tailored to the demands of smaller patient populations or local markets assume greater importance. Smaller batch sizes and lower product volumes are sufficient. Thus, new technologies are required, especially in crowded manufacturing suites, as manufacturers embrace new approaches rooted in increased efficiency, lean manufacturing, and continuous processing. Therefore, the challenge lies in implementing space-saving yet powerful equipment capable of creating a broad range of buffers simultaneously and in different capacities without any drop in quality or accuracy. This need can be met though automated buffer compounding systems.
Buddha (Biocon): Certain buffers are quite expensive to support process economics and affordable innovation. Hence, manufacturers are restricted to certain kinds of buffers that cost less. Buffer manufacturers should work on their process economics to support successful integration of desirable buffers into the process.
Ultee (Ulteemit BioConsulting): The total volume as well as the different types of buffers needed for a process can be challenging in terms of buffer preparation and storage. A couple of approaches are being used to address this challenge. First, an efficient downstream process will minimize buffer volumes by determining minimum needed for each step, and by applying the same buffer to more than one unit operation wherever possible. Secondly, the application of buffer concentrates that are diluted as needed at point-of-use have been helpful to some companies. Finally, the application of single-use storage devices, principally sterile bags in movable totes, has helped address buffer-storage challenges.
Advances in buffersBioPharm: Have there been any recent advances in the development and production of buffers or other process liquids?
Deorkar (Avantor): There is a trend to utilize pre-made, ready-to-use buffers. For example, when we supply a buffer to a biopharmaceutical manufacturer, that manufacturer relies on us to ensure the consistency and the quality of the buffer, based on our capabilities and regulatory compliance.
There is also a trend toward the use of ready-made buffer concentrates, which allow biopharmaceutical manufacturers to avoid using a large volume of the buffer at the beginning of the process. The buffer concentrate can be made in-house or it can be purchased from a supplier that has the capability to ensure its consistency and quality. Manufacturers may work with materials suppliers that offer pre-filtered control buffer solutions and other processed liquids, such as sodium hydroxide, hydrochloride, and glucose. These can be made, filtered, and provided in a concentrated form in a container that ensures there is no contamination. There are options to get these concentrates in single-use formats or returnable containers.
There is also the growing trend of the use of systems that deliver powder buffers directly to the biopharmaceutical manufacturing process as a means to streamline operations, reduce costs, and minimize the potential for contamination. The buffers come pre-weighed according to specification in a special protected, contaminant-free bag that can be added directly into the buffer solution tank. This is ideal for a facility using single-use manufacturing equipment, because the buffers come with the tubing, sampling tube, and sample tank included. Nothing else is required to test and start using the buffer--it’s ready-made. New systems have been designed to dispense free-flowing material to eliminate clumping that can damage equipment or pose a safety risk. This packaging also is compatible with contact-free near-infrared testing, which eliminates the need to break open the package to take physical samples.
Sanderson (Asahi Kasei): Inline buffer dilution systems have recently been incorporated into numerous low-volume manufacturing and continuous manufacturing facilities. Such equipment allows manufacturers, in certain cases, to produce conductivity and pH-controlled buffers ‘just-in-time’ from stock concentrates. The compact size optimizes resource allocation in new facilities and helps alleviate crowding in existing plants.
Ultee (Ulteemit BioConsulting): Automated instrumentation can be used to produce buffers as needed from basic stock solutions, simplifying preparation and reducing storage needs.
Single-use systemsBioPharm: How does the use of single-use technologies incorporate buffers and process liquids?
Ultee (Ulteemit BioConsulting): Single-use technologies are now in widespread use for buffer preparation and storage. They provide ease of use, portability, substantial reduction or elimination of cleaning costs, and lower capital outlays.
Sanderson (Asahi Kasei): The growing prevalence of single-use bags to store buffers is now being further leveraged by ‘just-in-time’ buffer dilution systems. Users can prepare multiple batches worth of stock buffer concentrate into a bag, and automated systems can dilute the buffer concentrates to final formulation on-demand. This reduces setup time in the plant, similar to a soda fountain, which can dispense any drink of choice from a single batch of syrup multiple times, each with the simple push of a lever.
The dilute buffer is immediately delivered to another single-use bag, from where it can be distributed to the downstream process in a timely fashion. This ‘soda fountain’ approach also obviates the need to store large volumes of WFI [water for injection] in multiple hold tanks throughout the plant--saving space in the modern biopharmaceutical manufacturing facility.
Deorkar (Avantor): Single-use buffer preparation tanks in the facility offer several advantages over traditional stainless-steel tanks. Namely, they allow one to change, on the fly, the amount of buffer that one needs. An operator can go from a 500-liter buffer capacity to a 5000-liter buffer capacity rather quickly, just by altering the single-use material. This also eliminates the possibility of contamination due to stainless steel, or the requirement to do cleaning validation and change-out. The buffer solution comes completely filtered and ready to use.
Buddha (Biocon): Single-use technologies reduce the cost and time associated with cleaning and sterilization operations conducted in manufacturing for stainless-steel vessels for various steps.
Article DetailsBioPharm International
Vol. 29, No. 4
Citation: When referring to this article, please cite it as S. Haigney, "The Importance of Buffers
in Downstream Processing," BioPharm International 29 4 2016.