Filtration

Membrane Adsorbers, Columns: Single-Use Alternatives to Resin Chromatography

Filtration membranes are used extensively throughout the biopharmaceutical industry for a range of applications, from coarse filtration to nanofiltration. Advantages of filter technologies include easy scaling, disposability, and (for many membrane filters) rapid and robust performance in a single-pass. The same advantages have been realized with membrane adsorbers. Chromatography resins are inherently disadvantaged by diffusion limits of the pores in chromatography media. Therefore, resin columns must be significantly oversized to match the performance of high productivity bioreactors. By comparison, membrane…

Membrane-Based Clarification of Polysaccharide Vaccines

Polysaccharide vaccines are essential for protection against infectious diseases, which remain an alarming cause of mortality. The first glycoconjugate vaccine for use in humans — a Haemophilus influenzae type b (Hib) conjugate — was licensed in the United States in 1987. This vaccine successfully reduced the incidence of invasive Hib disease in childhood and led to the further development of conjugate vaccines designed to prevent infection by other encapsulated bacteria (1). Polysaccharides are relatively complex carbohydrates made up of many…

Best Practices for Critical Sterile Filter Operation: A Case Study

A number of regulatory guidelines recommend preuse integrity testing of critical sterilizing liquid filters for aseptic processing (1–3). Before sterilization, a preuse test will confirm that a filter is installed properly and was not damaged during shipment or handling. Performing a preuse test after sterilization detects damage that may have occurred during the sterilization cycle. Testing after sterilization limits risk, so it is a practice applied based on risk assessment. Because it is perceived to reduce business loss risk, preuse…

Virus-Filtration Process Development Optimization: The Key to a More Efficient and Cost-Effective Step

Size-exclusion–based parvovirus filtration is an important step toward drug product safety in biopharmaceutical production. However, once a virus filter is in place, and the required virus safety is ensured, less attention typically is paid to its optimization within the process. That might seem odd given that virus filtration can be one of the more expensive downstream processing steps ($/g protein processed). Most likely, the lack of attention can be attributed to aggressive timelines, limited process development resources, and the virus…

Factors Affecting Sterile Filtration of Sodium-Carboxymethylcellulose–Based Solutions

Carboxymethylcellulose sodium (CMC), is widely used as an excipient in oral, topical, and parenteral pharmaceutical formulations. It increases viscosity (1–3), serves as a suspension aid (4), and stabilizes emulsions (5). More recently, applications for CMC in formulations that facilitate improved delivery of cytotoxic drugs and biologics have been evaluated (6, 7). CMC is manufactured in a broad range of viscosities, with grades typically classified as low, medium, or high viscosity. CMC grades can be divided further based on their degree…

Characterization of Postcapture Impurity Removal Across an Adsorptive Depth Filter

In the manufacture of monoclonal antibodies (MAbs), the first purification step following harvest clarification is normally protein A affinity chromatography because of its high selectivity for IgG and high process yield (1, 2). At this stage, a MAb is eluted from a protein A ligand at low pH and then held or adjusted to a low pH (pH ≤ 3.8) for a given amount of time before pH adjustment, usually ≥30 minutes, in a virus inactivation (VI) step targeted at…

Evaluating Adsorptive Filtration As a Unit Operation for Virus Removal

To date, the majority of recombinant monoclonal antibodies (MAbs) have been produced by mammalian cells. During such production processes, the potential risk of entrained viruses must be critically considered (1). Contamination can arise from animal cell lines or from adventitious viruses introduced during manufacturing. To ensure the viral safety of biotechnology products, companies can take four complementary approaches (2, 3): Using animal-component–free raw materials wherever possible Virus testing of master cell banks Virus testing of unprocessed harvest Performing downscale virus…

Evolving Clarification Strategies to Meet New Challenges

Increasingly efficient bioreactors allow biopharmaceutical manufacturers to achieve higher cell densities. That improved upstream efficiency has led to new purification challenges resulting from high product and contaminant concentrations as well as complex components. Therefore, harvest and clarification techniques are evolving to incorporate feed pretreatment, flocculation, and different filtration technologies such as normal-flow, tangential-flow, and depth filtration. The objective is to increase process capacities and filtrate quality, ultimately reducing biomanufacturing costs. New strategies for clarification of recombinant proteins (in particular, monoclonal…

Preuse, Poststerilization Filter Integrity Testing for Single-Use and Stainless-Steel Installations

According to current European Union good manufacturing practice (EU GMP), integrity testing of sterilizing-grade product filters should be performed preuse poststerilization (PUPSIT) and immediately after use. In addition, PDA’s Technical Report 26 states that preuse integrity tests are preferably performed after filter sterilization. Performing an integrity test of an already sterilized product filter in-line requires wetting the filter while maintaining the downstream side sterile. The test gas must also be evacuted on the downstream side throughout testing maintaining sterility. The…

Diatomaceous Earth Filtration: Innovative Single-Use Concepts for Clarification of High-Density Mammalian Cell Cultures

In the past decade, biopharmaceutical manufacturers have demonstrated major improvements in monoclonal antibody (MAb) production, exhibiting product titers frequently in the range of 5–10 g/L using standard fed-batch mammalian cell cultures (1, 2). Increased product yields allow for smaller-scale production vessels. With 2,000-L single-use bioreactors already commercially available, single-use manufacturing of biomolecules becomes more and more an option. Other recent developments in the biopharmaceutical industry — e.g., drugs for smaller indications and more potent drugs allowing for lower dosages —…