By Randi Hernandez, BioPharm International
Humans represent the greatest risk for microbial contamination in an aseptic process.
Aseptic processing has garnered some increased scrutiny from FDA in recent years, primarily because it is considered a high-risk activity by the agency, says Rainer Newman, consultant at Aseptic Process Technology, LLC. In addition, says Satish Singh, research fellow and group leader at Pfizer, “Microbiologically-related recalls have always been a significant portion of the enforcement actions by FDA.” In fact, more than 75% of FDA recalls during 2004–2011 involved sterile products, and approximately 80% of these recalls were linked to “lack of sterility assurance.” Many of the remaining 20% of recalls were attributed to microbial contamination or a failed fill/finish product test (1). Although packaging failures factored into a majority of the “lack of sterility assurance” cases, many of the remaining contamination cases were associated with GMP issues or manufacturing errors such as incomplete sterilization or nonsterile components being added to sterile products (1).
The large-scale meningitis outbreak in 2012 has been attributed to poor aseptic processes, when contaminated vials in lots of preservative-free methylprednisone acetate sickened 751 people and killed at least 64 people (2). Although states currently oversee the activities of compounding pharmacies, FDA released new draft guidance documents in February 2015 seeking to exert more regulatory control over drugs produced by state-licensed pharmacies, federal facilities, and outsourcing facilities. The documents released by the agency state that medications compounded in an outsourcing facility “that meet certain conditions may be entitled to exemptions from certain provisions of the Federal Food, Drug, and Cosmetic Act (FD&C Act), including the new drug approval requirements and the requirement to label drug products with adequate directions for use” (3).
Just because validation of a sterile effluent typically occurs under the “worst-case scenario” tenet, it does not mean that facilities should operate with this frame of mind when ironing out their aseptic processing capabilities. Negative agency inspection, increasing operating costs, and poor media fill results are among the reasons many manufacturing organizations are deciding to update or replace aging aseptic processing equipment. Many newer facilities, such as SAFC’s new antibody-drug conjugate-focused floor in its St. Louis, MO campus, have spaces that are designed to handle media fill for various types of products and have isolators for both highly potent compounds and biologic products.
While investigational medicinal products are not typically expected to be validated at the same standards as are products for routine production, sterile products must have validated processes “of the same standard as for products authorized for marketing,” according to the European Commission’s EU Guidelines to Good Manufacturing Practice: Medicinal Products for Human and Veterinary Use Annex 13, Investigational Medicinal Products (4).
Environmental monitoring, no matter how necessary it may be, is always an intervention in the process, notes Newman. There are various schemes and equipment, however, that can support minimized interventions when manufacturing sterile biologics in a controlled environment, he says.
Environmental monitoring, when it involves personnel moving in and out of the suite, can actually increase contamination risks if performed too frequently, asserts Singh. “Suites are qualified to handle a certain maximum number of people, but it does not mean that the maximum personnel load should be used, especially for long periods of time, whereby the air handling systems may be overwhelmed.” Singh adds, “Routine monitoring activity is an integral part of the normal processes and should be qualified as such.” Smoke studies are often performed to ensure a facility is meeting expectations for air balance and airflow in aseptic areas.
Clean water requirements
The demand for high-quality water for aseptic processing is of paramount importance, as water is not only an ingredient in many aseptic formulations, but is also as a cleaning agent in cleanrooms (5). Microbial, chemical, or endotoxin contaminants in feed water sources can occur in excess of a system’s ability to clear them, and this has periodically been a problem with water sourcing, says Newman. A concise environmental monitoring program can help a manufacturer assess product bioburden that may be attributable to water-derived organisms.
The most common introduction of contaminants by operators in aseptic processing is during set up, during interventions, and during material additions, notes Newman. Failed media fills are often the result of an operator action, he adds. Singh says that humans most frequently introduce contaminants when interventions are required on the line, during filling. “Interventions can be repeated, for example, if sampling for fill-weight check is not automated,” Singh notes. “Or, they can be episodic, [such as] if a vial falls over or gets stuck in transport, for example. Compounding, if not carried out properly, can also introduce microbial loads. Normally, these would be filtered out, but can [still] result in high prefiltration bioburden levels.”
Future GMP initiatives should focus on the minimization of human intervention in the aseptic process, suggests Bill Hartzel, director of strategic execution at Catalent Pharma Solutions, who says, “Humans are among the highest contributors to microbial and particulate contamination.” According to Hartzel, expanded use of isolators and increased automation will help mitigate the risk of product adulteration.
Protecting drug product from microbial contamination is a key concern when making biologics, which is why aseptic filling typically occurs in a positive pressure isolator. In a closed system, positive pressure is generally used within an isolator (wherein air flows out of the isolator) to protect biologics from outside contaminants that may be airborne in the environment. Conversely, negative pressure inside an isolator is used when dealing with a highly potent product to prevent egress of toxic material out of the closed system. Concerns related to operator safety exist when dealing with highly potent or cytotoxic drugs, such as is the case with the manufacture of antibody drug conjugates (ADCs) with cytotoxic payloads. To protect the worker making these specific types of ADCs, a more complex, negative pressure isolator is typically used, notes Newman. Gary Partington, technical sales and marketing manager of Walker Barrier Systems, says that an isolator blower or fan pulls air through a safe-change high-efficiency particulate air (HEPA) filter into the isolator and out through a safe-change double HEPA filter into the facility exhaust system. “If there is a leak in this isolator, the negative flow keeps the potent material from escaping,” notes Partington. For highly potent materials, says Singh, “isolator technology is a basic requirement.” Bioconjugates must be assessed for compatibility with processing equipment, Singh adds, and for these products, as well as with all biologics, “light sensitivity, interfacial stresses, and temperature impact must be assessed.”
The chances of contamination by operator are greatly reduced by incorporating automated blow-fill-seal (BFS) technology for the aseptic preparation of sterile pharmaceuticals. The container closure is automatically formed, filled, and sealed within the confines of a class A internal environmental in a matter of seconds, which drastically reduces the risk of contamination. While the manufacturing of the final product may benefit from this contained process, Hartzel highlights that feasibility studies of small quantities of drug product comparing the bulk substances to the filled product in a BFS container may be beneficial, as the inherent steps in the BFS process are significantly different than they are in traditional vial filling. “First, the BFS process uses heat to convert the virgin plastic pellets into a vial and the filling takes place seconds after the container is formed,” says Hartzel, emphasizing that the heat of the process could potentially impact thermally sensitive biologic drugs. “The second caveat is that plastics are semipermeable and are not impervious like glass,” Hartzel adds. Manufacturers must understand how storage conditions affect permeation rates and design applicable stability programs.
Singh agrees that products manufactured using BFS have to be compatible with exposure to momentary high temperatures as well as long-term exposure to the polymer, including migration of oxygen in and water out. BFS technology is characterized by an efficient heat transfer and rapid cooling process within the body of the container, hence in a matter of a few seconds, the temperature of the molten plastic (~385 °F to 450 °F) equilibrates to the mold temperature (80°–90 °F), says Hartzel. “There are multiple factors influencing temperature of the drug product during fill, including wall thickness, fill speed, surface-to-volume ratio, and temperature of the incoming variables. By controlling these variables, you can keep the temperature from spiking to less than 90 °F,” he says.
Singh adds that in spite of the concerns about thermal stress on the formulation of biologics, the short heat stress in BFS may be acceptable, as long as it has been evaluated and addressed during the development process—but the long-term compatibility concerns remain. Systems can be added to a standard BFS system that can minimize the heat impact, notes Tim Kram, general manager, rommelag. “How much heat is added to the system is a function of container design, type of plastic resin used, and the fill volume,” he says. “The product temperature can be controlled to the point of fill and heat added to the system can be removed after filling. For most products and fill volumes, it is possible to keep the final filled product temperature under 20 °C (68 °F).” Kram says that regardless of the presence of systems to minimize the impact of heat on product formulation, some biologics may still not be compatible with a BFS system.
Cleaning and disinfection of aseptic areas
Daily or weekly cleaning of aseptic processing areas is usually appropriate, says Newman, depending on the level of activity in the area. He explains that cleaning regimens are rather detailed, have to be validated, and must periodically be requalified. Current disinfection protocols for an isolator commonly make use of vaporized hydrogen peroxide (VHP), although according to Newman, it is “questionable if VHP should be considered a sterilization process or a high-level disinfectant.” Partington notes that isolators are generally validated to a 106 sterility assurance level (SAL), which he says “is far better than a cleanroom.” VHP reduces the availability of the isolator, however, due to the time needed to expose the isolator, evacuate the VHP, and allow for aeration. Hydrogen peroxide (H2O2) cleaning of an isolator, therefore, reduces the output of the isolator line, at least for a small time. “H2O2 is absorbed by plastic materials in the isolator and [these materials] need time to outgas so that the residual H2O2 level in the isolator is 1 ppm or less before processing can begin,” Partington explains. Singh points out that newer technologies, such as catalytic converters, are being developed that can speed up the cycle time to achieve the target residual levels of H2O2, improve turnaround time, and consequently, improve the overall utilization of isolators.
Single-use containers for aseptic processing—such as filters, tubing, connectors, and bags to hold bulk products—are already relatively common in aseptic filling, and can also help keep contamination events low. Most of these items are pre-sterilized. Other product contact parts, such as pumps or needles, are often dedicated to their specific processes, says Singh, but “even in these operations, single-use systems are being introduced.”
The introduction of new containers
While all containers and closure systems require a material compatibility, extractability, and container-closure integrity evaluation, according to Newman, problems can arise when a manufacturer is considering changes in container-closure design. “New containers that have unusual or novel dimensions, shapes, or other attributes may impact the design and function of filling and other handling equipment,” Newman asserts. “Depending on the change, there may be more fundamental challenges, e.g., sterilization of materials and components.” To determine if any of the packaging components have a negative impact on the product, the product is typically tested in its final packaging format under controlled conditions, says Kram.
New container presentations and closures can offer innovative drug-delivery solutions, but they can also introduce variables into the process of sterile filling. “The market space has changed, and the delivery of the medication is rising in importance,” Hartzel observes. “In addition, the recent manufacturing challenges of traditional glass vials have opened the minds of [people] in the market to explore new technologies to improve drug manufacturing and container-closure systems.”
Despite the willingness of industry to try new materials, Singh says that new containers/closures are fairly rare in sterile products, and Type 1 glass is likely to remain the industry workhorse for a while. “For new containers/closures with new contact materials, development studies would have to be performed to determine compatibility (chemical and physical) with the intended final product, providing adequate stability with low risk [for] leachables.” The new container or closures would also have to fit with the processing facility with change parts as required, as well as provide a significant added benefit, Singh adds.
New product contact materials or components are generally tested for extractables under exaggerated-use conditions of solution composition, temperature, and time of contact, says Singh. “Preferably, this is something that the vendor of the component performs and has available as a data packet for the user. The user of the component can then assess these compounds (i.e., extractables) for safety and toxicity, and make a risk-based decision to monitor specific species under actual-use conditions (i.e., leachables). In this case, method development for detection and qualification of the leachable in the product solution would be required once the compounds of concern have been identified.”
Filter integrity testing
According to Newman, there are two camps of thought on when filter integrity testing should be done. Testing post-use is something that is done every time. Pre-use testing of filters, however—especially pre-use, post-sterilization testing—is only required depending on whom you ask, as Europe and the United States have differing views regarding the risks and benefits associated with pre-use testing of filters. Europe requires pre- and post-testing for filters for some products, and the US is expected to follow suit. Singh says that for sterilization filters, both pre-use and post-use testing is common practice. For bioburden reduction filters, however, post-use is most common, and pre-use “may be dependent on the procedures adopted by the company.”
A filter’s bacterial retention capabilities post-use must be tested through qualification and validation procedures, by the manufacturer and the final user, respectively. Validation of a sterile filter to see how it affects a processing stream can include various elements, including integrity testing, “fit-for-use” requirements, sterilization, stability, binding, compatibility, extractables and leachables, and retention (6). Filters, in particular, should be analyzed for removal of bacteria (such as challenge organism Brevundimonas diminuta) from the stream per ASTM 838-05, and investigators should be able to demonstrate that the process stream does not negatively impact the filter. The presence of extractables and leachables from compounds that may have moved from the filter to the process stream should also be assessed (6). Historical successes with “similar formulations, filtration dynamics, membrane types, and process parameters,” could help a sponsor satisfy FDA Phase I GMP Guidance requirements, but may not satisfy EU guidance requirements (6).
In case of disruption
In the event of a contamination, the question of when processes should resume relies on the disruption, according to Newman. It’s important to account for all elements of the disturbance—such as how long a room may have lost positive pressure—to determine the degree of the disruption and if a short disinfection process would suffice, or if a full room qualification will be necessary before manufacturing resumes. Partington points out that in the event of a power loss or if the blower on an isolator ceases, the isolator interior is protected by HEPA filters, so the disruption is not immediately disastrous. Nonetheless, he also says that both positive and negative pressure isolators need to be periodically tested for leaks, and gloveboxes should be examined and tested frequently.
1. S. Sutton and L. Jimenez, American Pharmaceutical Review 15 (1), pp. 42–57 (2012).
2. The United States Department of Justice, “14 Indicted in Connection with New England Compounding Center and Nationwide Fungal Meningitis Outbreak,” www.justice.gov/opa/pr/14-indicted-connection-new-england-compounding-ce..., accessed May 30, 2014.
3. FDA, “FDA issues new draft documents related to compounding of human drugs,” www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm434270.htm, accessed June 1, 2015.
4. EC, EudraLex, Volume 4 EU, Guidelines to Good Manufacturing Practice Medicinal Products for Human and Veterinary Use, “Annex 13, Investigational Medicinal Products” (Brussels, Feb. 3, 2010).
5. J. Chua, “Pharma’s thirst for pure, clean water,” www.eco-business.com/news/pharmas-thirst-for-pure-clean-water/, accessed May 22, 2015.
6. R.W. Acucena, “Defining a Strategy for the Validation and Qualification of Sterile Filtration Processes of Investigational Medicinal Compounds,” presentation at the PDA Metro Chapter Dinner, March 4, 2014.