In the Lab
Automatic Quality Assurance
The emergence of automated QA tools is a boon to industry
Q uality assurance involves some of the most labor-intensive assays in pharmaceutical development. Highly skilled chemists can end up tied to a bench for hours on end, methodically carrying out routine tests like stability or dissolution assays when they could be making a much more strategic contribution to the company. Recognition of this fact has driven increased interest in automation of every aspect of quality assurance (QA) testing, from stability assays to filtration to microbial detection. Technology vendors are meeting their customers halfway by increasing their offerings of equipment and supplies customized to the automation needs of the QA laboratory.
A case in point: Evaluating the physical properties of drug tablets is an important but time-consuming stage of QA testing. The company needs to understand everything about its drug-how it breaks down, how it decomposes, its analytes, its racemic mixtures, its dissolution times. A number of assays address these questions. Stability assays yield information regarding a drug's level of degradants and other impurities. Content uniformity assays are carried out to make sure each tablet contains the right amount of drug. And every manufactured lot of any oral dosage form, whether it is a tablet, a capsule, or some other type, needs to undergo a dissolution test to make sure that the drug dissolves properly at body temperature within the target time frame.
Done manually, each assay would require numerous samples taken at many different time points and put through a series of sample-handling steps, including filtration. Time points would need to be observed precisely. For a fast-release tablet that requires only one time point, it might make the most sense to do the assay manually. Normally, however, dissolution is monitored over an extended period like 24 hours. Already, this seems like a hardship. And when there are a number of samples being tested, it is hard to imagine how a technician who is not an octopus can handle all those samples simultaneously.
Enteric release tablets, which are increasing in popularity, add another layer of complexity. Because the drug releases much more slowly, it is exposed not only to the stomach, but also to the small intestine, the duodenum, and other parts of the body. In order to accurately reproduce those environments, the tablet must be exposed to a series of buffers ranging in pH from 1 to 5.6. Throughout, the temperatures must be maintained to within a tenth of a degree.
A Logical Solution
Automation is the logical solution for these routine, standardized, high-volume tests. Not only does automation take the drudgery out of basic QA tests, it can eliminate the potential for human error by making all sample handling procedures completely uniform. A fully automated system can replace the labor of one or even more than one analyst, freeing that person for more creative work in the company. Automation also improves documentation, because the instrument documents everything; no longer is the analyst recording data in a notebook.
One company offering automated workstations for the QA market is Caliper Life Sciences (Hopkinton, Mass.). A few of their relevant products are the Active Ingredient Processing Workstation (APW3) and the Tablet Processing Workstation (TPW3), each in its third incarnation in fourteen years. The APW3 dissolves pharmaceutical ingredients and is capable of filtration, dilution, mixing, and inline analysis via liquid chromatography (LC) or spectrographic methods. The TPW3 has similar capabilities but can handle larger volumes (50 to 500 mL) and has a rotor for high shear mixing. The real novelty of the newer workstations, however, is in the area of usability.
According to Dale VonBehren, Caliper's manager for pharmaceutical development and quality, the leap in terms of usability is major. "You had to be really skilled in automation as well as in chemistry... these products were typically purchased by automation groups. There's always been a certain level of automation for a long time since computers first came out. With the latest generation of TPW3 and APW3, we're crossing the chasm to being something that any analyst can do in their normal job. You don't need a widget person or an engineer. The tools are in a language that they can use."
Caliper is the successor of Biomark, a maker of customized robotic workstations. The company made a conscious shift toward off-the-shelf tools because the custom workstation concept did not have enough flexibility or interoper-ability for a growing industry. "You get customized automation, which is what you wanted, but you're the only one that has one. Support of that is expensive if it breaks," VonBehren says. Additionally, training is very specific, so a company can't simply hire technicians who know how to operate the system; personnel must be trained. Ultimately, Caliper decided to change its approach. "There can't be that many different ways to prepare a sample. What we've done is spend a lot of time listening to customers about what they wanted."
Focus on Filters
That's how we help in terms of manufacturing process-by identifying and characterizing contamination problems that happen in production.
-Siqun Wang, MD, PhD, global director of research and development, DuPont Qualicon
Remember the technician with eight arms? One of the technician's jobs is to filter out particulate matter samples at precise time intervals from six or eight reaction vessels so that the sample can be subjected to downstream analytics such as high performance LC (HPLC) or ultra performance LC (UPLC). Anyone who has ever handled a syringe filter knows that the more you hurry, the faster your filter will clog. This is where automation-compatible filtration supplies would come in handy.
Manufacturers such as Millipore (Billerica, Mass.) are answering this call. Millipore's Millex line of filters can be used either manually or with an automated system. Millex filters are compatible with a number of systems, including Caliper and Zymark, a division of Caliper. The stations hold large numbers of filters and deliver them to the sample handler, where the sample is pulled and automatically filtered. The filter is then discarded. For standard HPLC applications, 0.45-micron membranes are recommended. For UPLC, a 0.2-micron pore size is available. Prefilters can be used to remove larger particles.
Suspensions, which contain a large quantity of particles, are some of the more difficult formulations to filter. And those new-fangled extended release tablets can present difficulties, says Vivek Joshi, PhD, biochemical scientist consultant at Millipore. "Sometimes, formulations which contain large amounts of excipients for extended release applications give problems downstream. As the drug dissolves, the solution becomes viscous. Those types of dissolutions can be problematic to filter."
Millipore will soon introduce a Teflon filter membrane. Chemically modified to be hydrophilic, Teflon is compatible with the sample solutions. A membrane that is not chemically compatible with the sample may partially dissolve, allowing particles through that could add impurities to the filtrate.
Automation is the logical solution for these routine, standardized, high-volume tests. Not only does automation take the drudgery out of basic QA tests, it can eliminate the potential for human error by making all sample handling procedures completely uniform. A fully automated system can replace the labor of one or even more than one analyst, freeing that person for more creative work in the company.
In traditional microbiology, samples are taken and cultured for contaminating organisms, a process that can take days or weeks. While this is fine for retrospective applications, it is problematic, to say the least, for a fast-paced development operation that works in real time for every other test and assay. Speed is the driving force behind automated systems for microbial detection, and there are a number of strategies for turbocharging these assays.
Celsis, Inc. (Chicago) bases its microbial detection assays on adenosine triphosphate (ATP) bioluminescence-the same reaction that lights up a firefly's tail. ATP is contained in microbial cells but, obviously, not in an inert sample like a drug tablet. If microbial cells are present in a sample, the reaction will generate light that can be detected in a luminometer. An enhancement to the reaction takes advantage of adenylate kinase in the microbial system. Adenosine diphosphate (ADP) is added to the reaction mixture, and adenylate kinase from the microbial cells converts ADP to ATP, thereby boosting the bioluminescent reaction and the readout on the detector.
AKuScreen, developed by Celsis, utilizes this approach. "This is the only rapid method that can detect bacteria, yeast, or mold in 24 hours... that's a realistic time for people who are using it on a daily basis," says Lori Daane, PhD, vice president of scientific affairs at Celsis. The company received the Food and Drug Administration's sanction last August when the agency accepted GlaxoSmithKline's New Drug Application for Veramyst nasal spray, an application supported by Celsis' Rapid Microbiological Method.
The RiboPrinter product line from DuPont Qualicon (Wilmington, Del.) is another rapid, automated approach to microbial testing that focuses on good manufacturing practices (GMP). GMP requires that manufacturers who detect contamination identify its source. That's where the RiboPrinter comes in. A colony is transferred from a plate onto the reagent strip and, in eight hours, the result is on a screen. "That's how we help in terms of manufacturing process-by identifying and characterizing contamination problems that happen in production," says Siqun Wang, MD, PhD, global director of research and development for DuPont Qualicon. The RiboPrinter is compatible and compliant with FDA 21cfr, part 11, and can handle eight samples at a time.
In effect, the RiboPrinter automates some amazingly complicated molecular biology, assays that were once time-consuming in the laboratory. "When I did Southern blots in the lab," says Dr. Wang, "I used bricks and paper towels to do the transfer. Our RiboPrinter basically automated the whole process... it gives you a genetic fingerprint of the bacteria."
Most methods for microbial detection are based on some sort of incubation of the sample. This always takes time, even if it is only 24 hours. AES Chemunex (Princeton, N.J.) has staked out the position that any time is too long to wait for important microbial detection results. "It's very important-and I would say critical-to get the results on a real-time basis," says Pascal Yvon, PhD, CEO of AES Chemunex. "Then QA people can react immediately and make appropriate decisions."
The AES Chemunex ScanRDI labels microorganisms using enzymes that diffuse through the membranes of the cells without destroying them. A product reacts with the enzyme, producing a fluorochrome that can't leave the microbial cell. The instrument detects the accumulation of the fluorochrome and gives results in 90 minutes.
"Most of the methods are growth-based methods," says Yvon. "What happens is that even though they are quicker than petri dishes, you still need a growth of microorganisms. The limitation of traditional methods or growth-based methods is that, by definition, you have to wait until it grows. With ScanRDI, you don't have growth of microorganisms. Because of that, we can get the results in a few hours, instead of days or weeks."
Biopharmaceutical processes have different requirements for microbial detection within the realm of QA testing. The process starts with a small amount of material, like a pot of soup, and ingredients are continuously added until the batch is completely scaled up. Each time anything is added to the batch, there's a risk of contamination. The more quickly contamination can be detected, the sooner the process can be stopped, cutting the company's losses before too much more is invested. Biopharma products are typically produced in mammalian cells, a potential problem for some technologies, such as ATP bioluminescence, that depend on an unbiased means for detecting living cells.
The emergence of automated instruments and supplies for QA testing offers a number of benefits to the industry. Increasing automation leads to increasing standardization. When a system is standardized, less time is wasted reinventing the wheel, and components-and opera-tors-can be interchanged easily and rapidly. When a PhD in computer science is no longer required to use the equipment, more people can access the technology and spend time working rather than training. Automation-compatible supplies like filters, tubes, reagents, and disposables support a smoother, faster, more efficient workflow. A key hitch to the wide adoption of automated technologies bears noting, however: acceptance by regulatory agencies. New assays must be validated against older standards, and in some cases, this takes time
It's very important-and I would say critical-to get the results on a real-time basis. Then QA people can react immediately and make appropriate decisions.