Contaminants, such as hairs and fibers, in a pharmaceutical solution are sometimes visible during postfilling inspection. If undetected, these undesirable materials can potentially threaten the manufacturer’s reputation and the patient’s well being. When a product fails inspection, manufacturing companies need to identify the cause of the contamination before production can continue. 

Many companies rely on various microanalytical techniques, along with digital photomicrography, to aid in contaminant identification. During microscopic analysis, personnel can attach a digital camera to the light microscope to capture digital images of the sample. 

The implementation of digital photomicrography has expanded the capabilities of microanalysis. But if used incorrectly, the technique can hurt more than help. Digitally altering images after they have been captured to make the contaminant more pronounced, or to highlight certain elements within the sample, reduces the validity of the scientific data. 

Without full confidence in the microanalytical data, pharmaceutical manufacturers risk missing important information that could help them identify the source of the contamination and ensure product safety. The strength of digital photomicrography is that it supports or validates the microscopists’ findings, which may be difficult to convey in writing. As a result, it is important to capture images properly without using image-editing or -manipulating software. 

The type and condition of the microscopes and equipment are crucial in capturing high-quality images. All microscopes must be cleaned and properly aligned. High magnification and high numerical aperture objectives, as well as high-resolution cameras, are critical when trying to capture images of microscopic contamination. Every lens within the microscope and camera must be particle-free. The cleanliness of the slides, coverglasses, instruments, and mounting media are all critical to image quality as well. Dust or foreign debris in the field of view, or air bubbles introduced during sample preparation, can resemble contamination to the untrained eye, thus causing confusion and leading to incorrect conclusions. 

Once the equipment has been checked and samples have been prepared, the final step in producing high-quality images is applying proper photomicrographic techniques. Samples are observed in a cleanroom to avoid cross-contamination. Initial examination of an isolated sample is usually performed with a low-magnification stereomicroscope or a high-magnification compound polarized-light microscope. Once the microscope has been turned on, the rheostat should be adjusted to the optimum color temperature and intensity using neutral density and color-correction filters. The compound microscope should be configured to Köhler-type illumination, which maximizes the amount of even illumination from inhomogeneous light sources. The last and most critical step is the proper adjustment of the aperture diaphragm, which controls the resolving power, depth of field, and contrast. 

Once the scientist has optimized the visual image while looking through the microscope’s eyepiece, he or she must adjust the camera settings and electronic controls to duplicate the eyepiece view on the monitor. Most digital cameras used with microscopes are operated by software that controls the camera settings and functionality. Typically,  camera software settings may need adjustment before the image may be captured. First, white balance allows the image sensor to adjust to the color temperature of the microscope’s light. Second, the exposure, or camera aperture setting, is adjusted to control the amount of light reaching the image sensor. Third, the saturation setting helps control the image’s color intensity. Finally, contrast adjusts the tones in the image, and can be used to match the adjustments made with the aperture diaphragm. These settings should be adjusted in an effort to match what is seen through the microscope eyepiece with the preview or “live” view in the software just before capturing the image.

The main goal of capturing images through the microscope is to achieve an image that accurately represents the view seen through the eyepieces. Image-editing and -manipulating software should never be used to compensate for poor microscopy. Instead, personnel should use proper microscopy techniques to ensure quality images. Accurate images of contamination, along with analytical data to support the images, provide a solid understanding of the source of the problem, and ultimately help the manufacturer take appropriate steps toward corrective action. 

Kristen Wiley is a senior research microscopist at McCrone Associates, the analytical division of the McCrone Group, 850 Pasquinelli Dr., Westmont, IL 60559, tel. 630.887.7100, 

. Wiley is also an instructor of sample preparation, isolation, and manipulation at Hooke College of Applied Sciences, the education division of the McCrone Group.

Articles

In the Mixer

The implementation of digital photomicrography has expanded the capabilities of microanalysis for quality control. But if used incorrectly, the technique can hurt more than help.

Best Practices for Digital Photomicrography of Pharmaceutical Contaminants

When a process does not produce the expected results, or when a piece of equipment behaves strangely, even experienced personnel sometimes may be at a loss to understand the reason why. 

’s “Troubleshooting” column is a forum to discuss production problems. Readers  submit anonymous questions, which equipment vendors and industry professionals  attempt to answer. In this way, the column may help promote greater understanding of the industry's products and processes.

Q: We want to fill one of our oxygen-sensitive products inside an isolator system. Can we run an isolator with pure nitrogen and defined humidity? 

A: Yes. From a technological standpoint, particularly with regard to control technology, rendering the isolator volume completely inert and preventing oxygen-sensitive products from undergoing chemical reactions within the isolator do not pose problems. These goals are achieved by implementing the pressure control inside the isolator through a nitrogen-operated control valve. In this approach, the isolator, which is designed as a closed-ventilation system, is operated with nearly 100% recirculated air. This system is different from the conventional design, which relies on the addition of fresh air to control temperature, thereby discharging internal thermal loads and using the exhaust air to control pressure.  

In a closed-ventilation system, leakage losses of the entire system have to be compensated by a controlled nitrogen supply to maintain the required pressure. But this approach, and the need to discharge internal thermal loads, requires the installation of cooling coils in the recirculation plenum. In addition, the mouse holes need a specific ventilation design (i.e., a pressure sink) to prevent excessive escape of nitrogen into the staff’s workspace.

Moreover, it is necessary to explain what is meant by defined air-humidity requirements. Running the system with nitrogen typically generates air humidity of < 10%. If, however, specific products require filling at a humidity of 45% ± 10% at 20 °C (i.e., 68° F), for example, the concept needs to have a system for controlling the nitrogen supply and simultaneously triggering nitrogen moisturization as a carrier gas. This task certainly is not easy with regard to control technology, but it can be accomplished.

—Robert Ehrhart, engineering department head for Optima Group Pharma

If you have a problem with your equipment or process, an industry expert may have the solution. Please send your question to 

 and we may be able to provide an answer in a future issue. All questions will remain anonymous.

Troubleshooting

We want to fill one of our oxygen-sensitive products inside an isolator system. Can we run an isolator with pure nitrogen and defined humidity?

A Nitrogen-Filled Isolator?

ACS Valves 
 Rotary feeder improves conveying efficiency


 The ACS Valves Aero-Flow series of rotary feeders is designed to convey pharmaceutical ingredients efficiently. Air enters the feeder through its two endplates. As the air circulates around the endplates, the air pressure increases and prevents the ingredients from getting into the feeder’s seals and bearings.

Air passes through a slot in the bottom of each endplate into the feeder housing and mixes with material being conveyed by the 10-vane rotor. The feeder thus aerates the material and helps it to flow freely. The aeration also helps to keep sticky or abrasive ingredients away from the feeder housing, endplates, and rotor, thus reducing wear on the unit.

In addition, the rotor design prevents material from building up inside the feeder. The precision tolerance of the 10-vane rotor design inside the unit prevents excess air from passing through the valve.

L.B. Bohle
 Cone mill increases throughput


L.B. Bohle’s BTS high-speed cone mill has a new impeller design intended to help manufacturers increase throughput by more than 50% on low-density materials, compared with traditional mills. Standard impeller designs consist of a straight bar that relies mostly on its own centrifugal force and the static pressure of the material above. Bohle’s impeller consists of two flat bars curved into the direction of rotation. The curved impeller pushes material into the screen, and this forced movement helps to increase the rate at which the material moves through the screen, says Martin Hack, the company’s vice-president and general manager.

Bohle provides a simple tool to allow users to remove the mill’s screen and impeller. The entire mill head also can be removed and cleaned in an autoclave. The mill is delivered with a mobile, height-adjustable cart that allows the machine to be docked easily with containers of various sizes.

PharmTech's monthly newsletter, Equipment and Processing Report, reviews the Editor's Picks for the April 2011 edition from ACS Valves and L.B. Bohle.

April 2011 Editor's Picks: Products from ACS Valves and L.B. Bohle

Drugmakers sometimes are reluctant to adopt new, and potentially superior, process technology for fear of the regulatory response. Such hesitation may reflect an incomplete understanding of quality by design (QbD), which partly is intended to encourage process improvements. To find out how well industry is applying QbD, and what benefits the approach can bring, 

 talked to Moheb M. Nasr, director of FDA’s Office of New Drug Quality Assessment.

EPR: How do pharmaceutical facilities use QbD and risk analysis to develop compliant manufacturing processes? 

Nasr: The firm usually conducts a risk assessment of the manufacturing process and  the key critical quality attributes of the product prior to developing the control strategy. The strategy can be based on extensive experimentation or on in-house prior knowledge of the formulation and manufacturing process. A control strategy that’s developed based on conducting risk assessment, product and manufacturing-process understanding, will lead to better control of the process and minimization of process variability. 

EPR: How much does QbD rely on established technology, and how much does it depend on new or emerging technology?

Nasr: All of these tools and approaches have been available for a long time. What was lacking was a commitment from industry to systemically use the QbD approach, appropriate guidelines, clarity of regulatory expectations, and business justification. There is no need to wait for new technologies. Having said that, I would argue some of the new approaches to development and manufacturing, such as continuous manufacturing, more reliance on modeling to develop a quality-control strategy, and real-time release testing, will provide added benefits. All of these things that are not routinely used now will help take QbD implementation to a new level. 

EPR: What have we gained during the time that QbD has been established?

Nasr: We as regulators have more confidence in the quality of pharmaceutical products that are developed and manufactured using QbD because we know they were developed based on good science, based on the relevant risk to the patient, and on a control strategy that provides higher assurance of quality. We also are more aligned with international regulators about how to evaluate quality in regulatory submissions. 

Using quality risk management in association with, or as part of, QbD helps industry better use resources during development. That means focusing more on areas of high risk, and less on areas where there is no risk to the patient. QbD also provides flexibility in manufacturing operations. Under QbD, the manufacturer can make changes to the manufacturing process without regulatory filings, as long as it is operating within the design space. Another benefit is the industry’s ability to reduce the cost of end-product testing because it relies more on real-time release testing. Also, because of the knowledge learned during development and the flexibility of the regulatory approach, the manufacturer can scale up the manufacturing process without waiting for more expensive experimentation and regulatory filing.

EPR: Is FDA ever reluctant to accept process controls developed through QbD?

Nasr: No. It all depends on providing an appropriate scientific justification for the proposals. If there is a lack of sufficient information, we ask for clarification and additional information. But if the information is there, we are happy to provide such flexibility. 

In the last few years, the agency has been taking a more proactive approach by learning more about new and upcoming technologies before they are implemented and included in regulatory submissions. For example, the concept of continuous manufacturing is becoming very important. My office, in the last few years, participated in collaborative research with the University of Washington in Seattle to better understand the use of microreactors and continuous manufacturing. That was done to allow our reviewers to have a better understanding and to be able to evaluate the technical information if and when [it is] submitted in regulatory filings.

Also, I have been going to meetings and workshops and explaining how the current regulations are applicable to new technologies. There is always a concern from industry: “Can we use this new technology with the existing regulation?” I felt like I had to explain the flexibility in the existing regulation that allows the use of new technologies. For the most part, industry is concerned about what can happen from the regulatory side. That’s why I feel like we should take an active approach and pre-empt their concern by explaining how new technologies fit within the existing regulation. 

EPR: How successful has the industry been in adopting QbD?

Nasr: I think industry is making a great effort to better develop and design manufacturing processes. I think the area that needs more work is the development of a modern quality strategy that is appropriate for these new technologies, rather than relying on the old checklist approach to control strategies. More work is needed to make existing quality systems more aligned with the QbD approach and new technologies. I think that can be done by adopting and meeting the expectations of ICH Q10. 

Production Lines

To find out how well industry is applying QbD, and what benefits the approach can bring, Equipment and Processing Report talked to Moheb M. Nasr, director of FDA?s Office of New Drug Quality Assessment.

Equipment and Processing Report-04-20-2011

Best Practices for Digital Photomicrography of Pharmaceutical Contaminants

A Nitrogen-Filled Isolator?

April 2011 Editor's Picks: Products from ACS Valves and L.B. Bohle

Are Drugmakers Using Yesterday's Quality Strategies?