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With the health and wellbeing of end customers on the line, pharmaceutical manufacturers put ultra-pure water systems to the test.
By Sarah Fister Gale
Bacteria love water. In the water systems of pharmaceutical manufacturers, controlling bacteria requires vigilance and careful planning, from design through daily operation.
Pharmaceutical-grade water systems are some of the most carefully designed and monitored water systems in any industry. This water is used in the cleaning of delicate pharmaceutical manufacturing equipment, as well as being the most frequently used ingredient in drug manufacturing for ingestible and injectable medical products used by the weakest and most vulnerable consumers. As a result, it is highly regulated and operators are required to rigorously test and monitor water quality constantly to ensure standards are being met.
Pharmaceutical water quality standards are dictated by the U.S. Pharmacopoeia (USP), the official public standards-setting authority for all prescription and over-the-counter medicines, dietary supplements, and other health care products manufactured and sold in the United States. All pharmaceutical water systems must be validated to demonstrate that they meet, and will continue to meet, their quality specification as defined by USP, which lays out the guidelines for testing and establishes minimum purity requirements for water quality used in these products.
Unlike electronics industries, which focus on managing particulate contaminants in their ultra-pure water systems, pharmaceutical facilities are more concerned about microbiological contaminants that can threaten the health and safety of consumers. This calls for a different type of testing and control system to guarantee quality and effectiveness. While contaminants in the microelectronics industry can weaken yields, bacteria in pharmaceutical water can cause illness and potentially death if left unchecked.
Multiple steps
A typical pharmaceutical-grade water system will include a pretreatment step to condition the water; initial filtration; a softening step; dechlorinization using activated carbon or bisulfite; a reverse osmosis step; and an ion exchange resin or electro-ionization to further purify the water, says Chris Fournier, vice president of marketing for Mar Cor Purification, a provider of filtration, water, and disinfection technologies in Lowell, MA. If there are additional requirements for the final product, further processing steps may be added, such as a 0.1-μm or 0.2-μm filter, or ultraviolet lights for bacteria control. “It can go on and on depending on the client,” he says.
The first steps, in which raw or municipal water is initially filtered, are important because this creates a level playing field for the additional water treatment efforts. “Raw water supply varies in quality,” says Chris Mach, biopharmaceutical marketing manager for Pall Corporation, a global filtration, separations, and purifications company based in East Hills, NY. The pretreatment step may include several filters to remove impurities, which can include particulates, inorganics, microorganisms, dissolved gases, and organic compounds.
These pretreatment steps reduce the effect of potential variations in feed water quality, minimizing the operating and maintenance requirements in the final treatment stages. The pretreatment step has little effect on contaminants such as anions, total bacteria count, TOC, and volatile components, but pretreatment must be effective to minimize plant operating costs and reduce the burden on later filtration steps. Pall’s clients typically use cross-flow microfiltration to remove small suspended solids, large colloids, and microorganisms from large volumes of feed water. These systems use backwash and air scrubbing techniques to minimize requirements for chemical regeneration.
Ultra-filtration membranes, typically made using hollow fiber or ceramic materials, are also incorporated downstream in the water system to further filter particles, bacteria, viruses, pyrogens (endotoxins), colloids, and large organic molecules.
The softening step replaces the hard ions with sodium to make the downstream processing run more smoothly and prevents minerals from forming a hard scale in the pipes.
Reverse osmosis is used in many pharmaceutical-grade water systems to further filter contaminants. Reverse osmosis is a separation process that uses pressure to force a solvent through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of other materials. This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 30-250 psi. Reverse osmosis offers many benefits to operators. It does not require the addition of chemicals, it has excellent throughput capabilities, and it delivers highly purified water.
“The membrane acts as an efficient barrier to all dissolved salts and inorganic molecules as well as most organic compounds,” says Mach of Pall Corp.
The dechlorinization step, in which chlorine is removed from water before it is used in processing, is one of the most delicate points in a water treatment system, Mar Cor’s Fournier points out, because the chlorine in the water kills the bacteria. “Once the chlorine is gone, your protection is gone.”
He notes that there are two common choices for dechlorinization. Activated carbon removes the chlorine without additional chemicals;, however, the carbon bed at the bottom of the carbon filter can act as a breeding ground for bacteria. “If you use carbon, you have to be extremely diligent about monitoring the filter,” he says.
With chemical dechlorinization, the bacteria are destroyed and there is no remaining harborage for bacteria to grow, but it is an additional chemical reaction in the water system that needs to be carefully handled. “Carbon versus chemical is a big decision for pharmaceutical facilities,” Fournier says. “Many times we consult closely with the client on their preference and design the final system around that choice.”
Tracking biological contaminants
Once a system is up and running, operators wage a constant battle against biological contamination. “Probably the most difficult to control and thus important contaminants to monitor closely in water systems are microorganisms,” says Pat Whalen, vice president of operations for LuminUltra Technologies, an ISO 9001:2000-certified dealer of second-generation adenosine triphosphate (ATP) monitoring products in Fredericton, New Brunswick, Canada. Those contaminants of concern include any form of bacteria, as well as algae, yeasts, molds, and other microbiological elements. Most bacteria in pharmaceutical water systems exist as biofilm that adhere to equipment surfaces. They may be found on virtually any surface in contact with water and, as a result, are not uniformly distributed.
“As soon as you sanitize a system the bacteria will start to build up again,” Fournier says. “Manufacturers are always looking for ways to design water systems that create less of a risk for bacteria. That’s the most difficult part of the design. It’s easy to remove inorganic and organic contaminants during construction of the system, but once you turn it over to the operator, keeping it in compliance is a lot more difficult.”
Even in robust systems, the most common source of bacteria in any treated water comes from the source or city water supply and seasonal issues can cause the biggest upsets, says Nissan Cohen, owner of Start-Up Business Development, an independent consultancy in Louisville, CO. For example, in summer months, the city water department will often increase levels of chlorine to deal with rising algae problems. Pharmaceutical companies using that water source need to be aware of the impact these seasonal concerns can have on their own water supply. “Municipalities are not obligated to report what they are doing to the water, so you can’t control it,” Cohen says.
Ineffective water treatment, a break or breakdown in the system, and dead legs where water sits and stagnates also can cause bacteria and biofilm build-up in the water system; poorly managed control systems, inadequate testing programs, or insufficient operator training can exacerbate the problem.
Sanitization strategies
Bacteria collection is inevitable, so a rigorous sanitization schedule is necessary to keep the system in compliance. “The biggest issue for pharmaceutical manufacturing facilities centers on the frequency of sanitization,” says Fran McAteer, vice president of quality at Microbiology Research Associates, a microbiology consulting, research, and testing services firm in Acton, MA. “All water systems need to be sanitized. The problem is that people don’t adhere to their sanitization schedule,” he notes.
A typical sanitization process using chemicals creates significant downtime, knocking out a system for 6 to 24 hours. “A lot of companies don’t like to have their systems down that long so they delay sanitization,” McAteer says. The result can be a build-up of biofilms and unpredictable contamination events.
Fournier notes that Tier 1 facilities tend to be very strict about sanitization schedules, whereas smaller operations may increase testing and monitoring to delay the cleaning step. “Every owner has their own validation protocol,” he says. “Some have more latitude than others.”
There are a variety of strategies for sanitization of a pharmaceutical-grade water system. For chemical sanitization processes, operators flush the water system with highly biocidal chemicals, such as hydrogen peroxide or bleach, and leave the chemicals in the system for an established hold time before flushing them out. This is followed by chemical testing of drain water to ensure that residual chemicals have dissipated and are not left in ports or pipes, McAteer explains. He points out that chlorine will break down on its own after a small amount of time, and hydrogen peroxide can be broken down using ultraviolet lights.
“Still,” he says, “some people feel that using harsh chemicals in a pharmaceutical-grade water system is too big a risk.”
Hot water is another alternative now being used by some facilities, Fournier says. As a sanitization step, facility operators bring the temperature of the water to 80°C and maintain it there for roughly an hour. “In pharmaceutical operations, 80°C is considered an acceptable sanitization technique,” he says. One of the benefits of hot water sanitization is the speed to completion because there is no rinse-out step.
“Hot water is a newer technique, so fewer processing operations use it now,” Fournier adds. “Chemicals are still considered very effective. It’s what most operations use because it’s effective, predictable, and the biodegradable chemicals are not hazardous.”
Ozone sanitization is another commonly used microbial disinfectant in water distribution systems. Ozone acts faster than chlorine to kill bacteria and is easier to remove once the sanitization process is completed, says Mischa Shifrin, president of Absolute Ozone, an ozone generator manufacturer in Canada. It can be conducted in much less time than chemical sanitization, enabling pharmaceutical manufacturers to reduce their downtime. “Ozone is an extremely aggressive oxidant and will destroy any bacteria that have survived the pretreatment and filtering,” Shifrin asserts.
The other benefit to ozone is that it has a very short half life. “In moderately warm water it will die in 10 to 12 minutes,” he says, noting that some users will heat the water or apply ultraviolet lights to guarantee its destruction, although he feels these are unnecessary steps. There are also monitors available on the market that will continuously measure levels of dissolved ozone in the water stream.
“Before implementing ozone, one should explore the amount of ozone required, and select a proper ozone concentration and type and size of ozone generator required,” Shifrin says, noting that quality systems as well as health and safety issues come into play around these decisions.
HPC vs. ATP
Along with effective treatment, testing plays a critical role in the management of any water system. Each site must have established standard operating procedures (SOPs), which can include daily or weekly tests at water supply and use points. In some facilities, tests correspond with batch production cycles.
“The effectiveness in managing a system can only be measured by having measurable results. In this case, an accurate indicator of total microorganisms is the best tool to provide confirmation of effective system operation and maintenance,” says LuminUltra’s Whalen. To prove compliance, operators must test bacteria and contamination levels in the water system frequently enough and in a variety of areas to verify water quality. The tests should be conducted at all drops in the system, which include dead end pipes, ports, and faucets leading off the system. “If you do not measure contamination, you cannot control contamination,” he concludes.
Depending on the pharmaceutical products being made, testing may be as frequent as every day for manufacturers of parenteral drug systems, or injectables; or less frequently for water systems used primarily for clean-in-place systems or Class One medical devices in which water is not a primary ingredient.
For decades, pharmaceutical facilities have relied on heterotrophic plate count (HPC) tests as the method for enumerating heterotrophic organisms in treated water. A heterotrophic organism is any organism that obtains nutrients by feeding off of organic compounds in the water. These tests use a low nutrient medium, such as R2A agar, in combination with a lower incubation temperature and longer incubation time to stimulate the growth of stressed and chlorine-tolerant bacteria. This is particularly important because in treated water, fast growing bacteria tend to be eliminated or injured by sanitization procedures, leaving slower-growing bacteria behind, McAteer says. Nutritionally rich media, such as plate count agar, support the growth of fast-growing bacteria but may suppress slow-growing or stressed bacteria found in treated water.
To test water samples for their heterotrophic microbial load, a water sample is filtered through a filter membrane, then the filter is rinsed to remove any existing bacteriostatic/fungistatic contaminants. The filter is then aseptically transferred to plated heterotrophic agar media and incubated at 37°C. The visible colonies that are present in the sample, grown from clusters, chains, and single cells of the heterotrophic bacteria, show up on the media and are quantified as total colony forming units.
This is a very effective testing method, giving facilities a reliable “present or absent” result of bacteria in the water; unfortunately, test results can take two to five days to fully bloom. That creates a number of obstacles for facilities operators. The most obvious shortcoming of these tests is that they force facilities to quarantine or hold finished product for days until test results can be verified, which extends the production cycle, requires additional storage area, and reduces the shelf life of a product.
A positive result can also leave operators without a lot of direction in identifying or eliminating the source of the contamination because the test results are so old. The contamination event could have been temporary, localized, or a result of a water-borne incident that happened that day.
For example, an operator may take a measure at a dead leg-or closed valve in the system-and find a high bacteria count that is the result of water stagnating in that dead-end pipe. “Once you flush the pipe, the bacteria may quickly pass out of the system, but you wouldn’t know that if you were waiting five days for test results,” Whalen says.
“The chief issue in controlling water system biological contamination is time,” he adds. “Current practices using culture tests drags down productivity and can be very expensive.”
A recent development in pharmaceutical-grade water system testing is changing that time problem through the slow but steady replacement of HPC tests with use of rapid techniques, such as the measurement of ATP. ATP is a molecule found only in and around living cells; as such, it gives an interference-free indication of total biological concentration. Applications of ATP tests are based on capturing the microorganisms, releasing the ATP from within the cell, and measuring the amount of bioluminescence generated when the released ATP is mixed with a solution containing the firefly enzyme luciferase. Light is produced within seconds and can be measured with a luminometer. The amount of light emitted from this reaction is directly proportional to the amount of ATP present. A high reading of relative light units (RLUs) indicates that a sample contains a high number of microorganisms, provided the background ATP level is low. Unlike traditional HPC testing methods, results from a bioluminescent reaction can be obtained quickly.
Because the results are available immediately, facilities operators can get on-the-spot information about their contamination status, instead of having to wait days for cultures to bloom.
“Rapid testing is certainly a trend that has been evolving in this industry and many others over the years,” Whalen says. LuminUltra manufactures a second-generation ATP test kit for ultra-pure water applications, which measures ATP at very low concentrations with no incubation requirement in minutes and at dollars per test. “As manufacturers become more efficient, they need to have access to information faster, and rapid testing plays a critical role in this regard.”
He notes that although rapid ATP testing for microorganisms has been successfully used for nearly 30 years in the food and beverage industry, the pharmaceutical industry is slower to embrace these test methods, largely, he feels, because of a lack of education about their availability and applicability. “The industry just doesn’t know there is a better way.”
Online monitoring
Along with bacteria testing, online monitoring of TOC and conductivity can be used to bring facilities real-time information about their contamination content so they know exactly when an event happens. “You can do that all online,” says independent consultant Cohen, noting that many facility operators are still hesitant to implement online monitoring due to a lack of knowledge or an inability to interpret the software results. “The pharmaceutical industry tends to take a conservative approach, but the FDA is advocating a more risk-based approach to contamination management. Online monitoring helps achieve that. It lets you control contamination before it becomes an issue.”
He also notes that continuous monitoring eliminates validation issues because you can prove the water system was always in compliance with quality standards.
Whalen agrees. “What is needed to control contamination is a single measurement that can be easily applied at any point in the process on a routine basis, with instant feedback that can allow operators to adjust treatment requirements as needed to maintain high product quality,” he says. “If quality and operation managers were able to gain accurate information in real time, issues could be resolved on the spot and raw materials-in this case, water-could be released faster, which would dramatically increase productivity, reduce risks, and improve product quality.”
Online TOC and conductivity analyzers designed for continuous monitoring of waters can deliver ongoing analysis developed to USP requirements, notes Christian Stark, head of marketing for Christ Water Technology Group, headquartered in Aesch, Switzerland. “They offer real-time information for conductivity and temperature so that operators can limit the impact of events and avoid errors due to sampling, handling, and transport.”
However, online monitoring has valuable but limited applications for these water systems. “Real-time monitoring is already in use for most of the quality relevant parameters such as TOC, conductivity, and temperature,” Stark says. For the microbiological issues acknowledged, though, no online monitoring devices are known so far.
In combination, however, real-time monitoring and timely bacteria testing can help keep any water system safe and in compliance, eliminating downtime and reducing contamination events, Whalen says. “We believe that access to better monitoring tools will lead to better management and preventive maintenance of water systems, ultimately resulting in greater efficiency, reduced production costs, and improved product quality for pharmaceutical manufacturers.”
Resources and contacts
Absolute Ozone Edmonton, Alberta, Canada www.absoluteozone.com
Christ Water Technology Group Aesch, Switzerland www.christwater.com
LuminUltra Technologies Ltd. Fredericton, New Brunswick, Canada www.luminultra.com
Mar Cor Purification USA Lowell, MA www.mcpur.com
Microbiology Research Associates, Inc. Acton, MA www.mra-bact.com
Pall Corporation East Hills, NY www.pall.com
Start-Up Business Development Louisville, CO 303-926-1866