The Benefits of Outsourcing Stability Testing

By Ryan Williams and Sean Gavor

By offering a suite of stability chambers, contract testing providers can help firms meet regulatory requirements for distribution into countries with different climate conditions.

A good partner will be able to offer sophisticated equipment, turnkey programs, and more

Unless your product is made and used within the same day, stability testing is required to demonstrate how long the product can be stored safely before it starts to degrade. It’s the science behind the expiration date.
In general, companies perform stability testing to look for evidence of degradation and the formation of impurities and to ensure that the active ingredients are still within specification. Tablets, oral medications, injectables, and topicals all need to demonstrate stability. Every formulation of the drug product must be tested, and each drug product is subject to a variety of tests.
Companies define the requirements for stability testing in each product’s regulatory submission. International Committee on Harmonization (ICH) guidelines recommend that all testing be performed at approximately the same time. This means that at every stability interval, samples must be pulled from storage and tested within a few days of the target date.
Fortunately, even stability programs that are run in house can be outsourced, so it is never too late to turn your stability testing over to a qualified partner.

Key Considerations

In addition to maintaining a more consistent workflow in the lab, managers may choose to outsource stability testing to minimize the risk of transporting samples. Temperature excursions may occur while the samples are in transit from the stability storage facility to the lab for testing and then back into storage. These changes have the potential to affect the test results and, therefore, the projected expiration date of the product.
Contract labs with on-site stability storage eliminate this risk and reduce the time samples are outside their stability chambers. It is these same stability chambers that offer the most compelling reason for outsourcing: Purchasing, qualifying, and maintaining stability chambers can be an expensive proposition.
Both reach-in and walk-in versions of stability chambers must be continuously monitored for temperature and humidity, and there must be mechanisms in place to regulate the temperature and humidity so that each chamber operates within specified limits. These requirements make stability chambers costly to install and maintain.
Contract providers will have chambers and backup chambers on an uninterrupted power supply, with backup generators and 24/7 monitoring systems that feature alarms and backup alarms to notify personnel in the event of a temperature or humidity excursion. They will also have the staff and resources to ensure the chambers are serviced, inspected, calibrated, and qualified regularly and to maintain the significant paperwork involved in keeping the chambers consistent with current good manufacturing practices (cGMP) and ICH guidelines.
In addition, by offering a suite of chambers, contract testing providers can help companies meet regulatory requirements for distribution into countries with different climate conditions.
The ICH has established four zones for stability testing, each with different specifications, limits, and time points. Zone I conditions are for products that will be distributed in the United States, Canada, the United Kingdom, and Northern Europe. Zone II includes countries on the Mediterranean such as Portugal and Greece and more tropical parts of Japan. Zone III conditions are hot and dry, for places such as Iran, Iraq, and the Sudan. Zone IV conditions are hot and humid, about 40°C and 75% humidity, simulating the rain forests of Brazil and many countries in Southeast Asia.
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Case study

Get Started with a Method Transfer

Method transfer can be as simple as having the contract lab run your protocol to demonstrate that the test can be executed accurately.

Small details must be determined prior to the execution of a stability program. Otherwise, your early data—and months or years of internal testing—may not be useful.

More complex stability programs should always start with a method transfer. This is used to demonstrate that the lab you’ve selected can produce accurate and precise results.
Even though your facility may follow GMPs, some early-stage stability methods are not formalized for outside use. Only validated methods should be utilized for stability testing. However, for some early stage programs the robustness of the method may not have been fully understood.
For example, Celsis received a method to be used for stability testing of a pharmaceutical product. While following the written transfer protocol, Celsis found that its results did not match those of the customer’s lab. The customer’s lab manager reviewed the instructions provided and confirmed that these were the same steps. But when the Celsis analyst talked directly with the company’s technician, the analyst learned that the tech had mixed the sample for longer than had been indicated in the provided method.
Small details like this must be determined prior to the execution of a stability program. Otherwise, your early data—and months or years of internal testing—may not be useful, and expiration dates may be affected.
Method transfer can be as simple as having the contract lab run your protocol to demonstrate that the test can be executed accurately and precisely. Some contract labs can also help you write a formal protocol if you do not have one. In either case, method transfer can be an important step to ensure that you can trust the accuracy of the results generated.

Extreme Testing

Some products may require non-standard storage at conditions for which a manufacturer may not have qualified chambers. Contract labs are not always limited by the standard or zone conditions, however. Ask if the provider has variable chambers capable of being qualified at non-standard conditions.
For example, a Celsis International client asked that a product be tested under extremely humid conditions. Celsis was able to create and qualify a difficult-to-maintain chamber condition of 40˚C and 90% humidity for this project.
Other examples of non-standard stability testing conducted to meet client needs include an environment with humidity below 20%—an extremely dry chamber—and a number of studies that cycled samples from minus 20°C to 40°C in 12 hours and back down to minus 20°C over the next 12 hours, repeating this up-and-down cycle every 12 hours for five days or more.
Some providers, including Celsis, also offer a special chamber for photostability storage. Photostability testing is required to demonstrate that the final packaging configuration is suitable for protecting a photo-liable product from photodegradation. Photostability can also be used during method validation to determine photodegradants during forced degradation studies.
Throughout the supply chain, there are containers on trucks or ships reaching very high temperatures during the summer months or freezing during a cold winter. Not all warehouses are climate controlled. And consider the large animal veterinarian who must keep all types of medications in his or her vehicle throughout the year.
Freeze/thaw and shipping studies are separate studies that can help evaluate overall stability. If your samples are found to degrade faster in higher temperatures, for example, a shipping study will identify the conditions at which the product can be shipped safely.
Even before a product is manufactured, a company may run a number of accelerated stability programs on formulation batches to evaluate the product’s feasibility. By using higher temperatures and higher humidities than expected, these accelerated programs are designed to predict the shelf life of a product prior to demonstrating it in real time.

Beyond its standard and specialized storage conditions, a good outsourcing lab will be able to offer a full range of chemistry and microbiological testing options.

Testing Support

Beyond its standard and specialized storage conditions, a good outsourcing lab will be able to offer a full range of chemistry and microbiological testing options. In addition to the assay, dissolution, and impurities, other common tests include pH, color, sterility, endotoxin, and preservative efficacy testing (PET).
Some multiple-dose containers of sterile products, such as IVs, have a resealable fabric. One aspect of stability testing for these types of products involves repeatedly opening the container and removing a dose to ensure that the correct number of doses is in the container, that the container seals up, and that the re-entry does not introduce contaminants.
Similarly, PET is required for multiple-use containers. PET ensures that over the life of the product the preservative will still be present and the bioactivity of the preservative will be maintained within specification.

What to Expect

When selecting a contract lab for your stability storage and testing program, choose one that is licensed with the U.S. Food and Drug Administration (FDA) and, as the FDA recommends, schedule an on-site audit, or at least make certain that third parties regularly review the lab’s facilities and systems.
Look for a comprehensive stability chamber qualification, calibration, and preventive maintenance program; qualified personnel running the program; and current, thorough SOPs, based on cGMP and ICH protocol, that govern every aspect of the program.
Discuss the lab’s process for maintaining files for studies. Is the system paper-based or electronic? What backups are in place? Ask what you can expect for reporting.
You should expect to receive a summary report at each time point. In some cases this will include a brief history of the testing along with a table showing the full results to date. At the end of the study, a full and final report should be issued.
Finally, you don’t want to be the lab’s first or only stability customer. It’s important that the partner you select can accurately anticipate and meet the testing requirements and volume your stability program entails. For example, Celsis has more than 30 years’ experience conducting stability studies, with 50 to 100 stability programs conducted simultaneously.
Contract labs invest hundreds of thousands of dollars in stability storage chambers, testing equipment, and qualification and maintenance of equipment. More money is spent on staffing, so they have the resources to jump in and do all the required testing within the proscribed time frame—be it every three months for a new product or three lots a year for a released product.
Best of all, the right contract lab will offer a turnkey program that means you won’t have to worry about the varying workload, temperature changes, chamber qualification, and reporting. When your program has been reliably transferred to the right outsourcing partner, the word stability will bring on of a feeling of calm.
Ryan Williams is manager of chemical sciences for Celsis in St. Louis, Mo. Sean Gavor is supervisor and metrology/stability coordinator for Celsis in Edison, N.J.

Editor’s Choice

1. Microbac Laboratories, Inc. Pharmaceutical stability studies. Microbac website. 2005. Available at: www.microbac.com/technical_articles/news_detail.php?news_ID=10. Accessed June 2, 2011.
2. Rignall A. Physical stability testing during the product development lifecycle. Pharmaceutical Outsourcing website. 2011. Available at: http://pharmoutsourcing.com/ViewArticle.aspx?ContentID=161. Accessed June 2, 2011.
3. Barron MD. Outsourcing stability testing: a tool for resource and risk management. Paper presented at: AAPS Workshop—Pharmaceutical Stability Testing to Support Global Markets; September 2007; Bethesda, Md. Available at: www.aapspharmaceutica.com/meetings/files/100/MichaelBarron.pdf. Accessed June 2, 2011.

Validation Principles

By Chung Chow Chan, PhD

Principles and Practices of Analytical Method Validation

: Validation of analytical methods is time-consuming but essential

Editor’s Note: This article is excerpted from a chapter that appeared in Pharmaceutical Manufacturing Handbook: Regulations and Quality, which was edited by Shayne Cox Gad, PhD. The book was published in 2008 by John Wiley & Sons Inc., which also publishes PFQ. For more information on the book, click on the image of the book's cover to the right. 
Validation of an analytical procedure is the process by which it is established, by laboratory studies, that the performance characteristics of the procedure meet the requirements for its intended use. All analytical methods intended to be used for analyzing any clinical samples will need to be validated. Validation of analytical methods is an essential but time-consuming activity for most analytical development laboratories. It is therefore important to understand the requirements of method validation in more detail and the options that are available to allow for optimal utilization of analytical resources in a development laboratory.
There are many reasons for the need to validate analytical procedures. Among them are regulatory requirements, good science, and quality control requirements. The Code of Federal Regulations (CFR) 211.165e explicitly states that “the accuracy, sensitivity, specificity, and reproducibility of test methods employed by the firm shall be established and documented.” Of course, as scientists, we would want to apply good science to demonstrate that the analytical method used had demonstrated accuracy, sensitivity, specificity, and reproducibility. Finally, management of the quality control unit would definitely want to ensure that the analytical methods that the department uses to release its products are properly validated for its intended use so the product will be safe for human use.

Current Good Manufacturing Practices

The overarching philosophy in current good manufacturing practices of the 21st century and in robust modern quality systems is that quality should be built into the product, and testing alone cannot be relied on to ensure product quality. From the analytical perspective, this will mean that analytical methods used to test these products should have quality attributes built into them.

Image courtesy of Thermo Fisher Scientific

Figure 1. Life cycle of analytical method

To have quality attributes built into the analytical method will require that fundamental quality attributes be applied by the bench-level scientist. This is a paradigm shift that requires the bench-level scientist to have the scientific and technical understanding, product knowledge, process knowledge, and/or risk assessment abilities to appropriately execute the quality functions of analytical method validation.
It will require three things:

• the appropriate training of the bench-level scientist to understand the principles involved with method validation and to be able to validate an analytical method and understand the principles involved with the method validation;
• proper documentation and understanding and interpreting data; and
• cross-functional understanding of the effect of their activities on the product and the customer (the patient).
• It is the responsibility of management to verify that skills gained from the training are implemented in day-to-day performance.

Cycle of Analytical Methods

The analytical method validation activity is not a one-time study. This is illustrated and summarized in the life cycle of an analytical procedure in Figure 1. An analytical method will be developed and validated for use to analyze samples during the early development of an active pharmaceutical ingredient or drug product. As drug development progresses from Phase 1 to commercialization, the analytical method will follow a similar progression.
The final method will be validated for its intended use for the market-image drug product and transferred to the quality control laboratory for the launch of the drug product. However, if there are any changes in the manufacturing process that have the potential to change the analytical profile of the drug substance and drug product, this validated method may need to be revalidated to ensure that it is still suitable to analyze the API or drug product for its intended purpose. (For more information, see the related article, “Perspectives on Method Validation,” in this issue.)
The typical process that is followed in an analytical method validation is as follows:

CONTAMINATION CONTROL | Cleaning Validation Procedures

It’s Clean, but Can You Prove It?

Validation and revalidation are key when establishing cleaning methods

ALL IMAGES COURTESY OF Lancaster laboratories inc.

Editor’s Note: This article is the second in a two-part series on cleaning validation methodology. Part one, “How to Improve Cleaning Processes,” appeared in our June issue.
Method limits, selection of cleaning techniques, and selection of method detection were addressed in the first part of this article. Part two will address method validation, the importance of stability for cleaning validation samples, when revalidation of a cleaning method is necessary, the use of correction factors, and how to handle failing results.
Once the basic cleaning procedure elements have been established (establishment of limits, cleaning procedures, master plan, cleaning protocols, development of analytical method), the method is ready to be validated.1 This section outlines typical components utilized to validate the analytical method. The validation components presented below are based upon International Conference on Harmonisation (ICH) and United States Pharmacopeia (USP) guidelines.
Accuracy/Precision: The accuracy of an analytical procedure expresses the closeness of agreement between the value that is accepted either as a conventional true value or an accepted reference value and the value found. The precision of an analytical procedure expresses the closeness of agreement (degree of scatter) between a series of measurements obtained from multiple sampling of the same homogeneous sample under the prescribed conditions.2
Accuracy/precision should be assessed using a minimum of three concentration levels, each prepared in triplicate. Accuracy/precision is typically performed with concentrations ranging from 80 to 120% of the final theoretical sample concentration (based upon the maximum contamination limit or MCL), although a wider range may be more appropriate in certain instances.

Swab accuracy determines a method’s ability to recover the compound of interest directly from the swab head.

There are various categories of accuracy/precision that need to be established as part of the method validation.

• Solution accuracy is the measurement of the compound of interest added directly to the extraction solution. Reference standard solution is spiked directly into the diluent to prepare the three levels of concentration. Solution accuracy is performed as a control—usually in triplicate—to prove recovery of the analyte from the extraction solution. This recovery can then be compared to both swab and surface accuracy recoveries. If rinseates are being analyzed, this test is the only one needed to prove accuracy/ precision.
• Swab accuracy determines the method’s ability to recover the compound of interest directly from the swab head. These studies are performed by directly adding standard material to the swab head and then extracting as per the analytical method. Typically, three replicate-spiked swabs are prepared at the high and low concentrations, while six replicates are prepared at the 100% level.
• Surface accuracy determines the method’s ability to recover the compound of interest directly from a defined surface. Coupons of the defined surface material are spiked with reference standard at the three concentration levels mentioned above. The area of the coupon spiked with standard is dependent on the actual cleaning procedure and the surface area typically sampled after manufacturing. Typical surface areas sampled are 25 to 100 cm2.

Acceptance criteria should be evaluated and determined during the development of the analytical methods. Many factors influence the establishment of appropriate criteria, including the surface being swabbed, MCL, type of swab, and instrumentation. Intermediate accuracy/precision should be performed by a second analyst repeating the accuracy/ precision tests listed above. If multiple surfaces are involved in the validation, the second analyst can perform accuracy/precision on select surfaces (worst case) if appropriate.
Linearity: The linearity of an analytical procedure is its ability, within a given range, to obtain test results that are directly proportional to the concentration (amount) of analyte in the sample.2
A minimum of five concentration levels are typically evaluated, with duplicate injections at each level. Concentrations ranging from the limit of quantitation to 200% of the MCL are typically evaluated during validation. Acceptance criteria are generally based upon either the correlation coefficient or the coefficient of determination of the linear plot. In addition, criteria can be established around both the slope and Y-intercept of the plot.

Table 1. Summary of Typical Validation Components (Click to Enlarge)

Specificity: Specificity is the ability to assess the analyte unequivocally in the presence of components that may be expected to be present.2
Swab type and surface type are typically evaluated to determine if interferences are present in the method. Although each of these components is typically examined during method development, they should be included in the validation process and shown, under protocol, to have little or no interference. Swabs and surfaces are prepared as per the method without the introduction of the analyte of interest. Interference from either the swab or surface should be less than 10% of the MCL. Lower limits for specificity may be appropriate depending on the method conditions.
Limits of Detection and Quantitation: The limit of detection (LOD) of an individual analytical procedure is the lowest amount of analyte in a sample that can be detected but not necessarily quantitated as an exact value. The limit of quantitation (LOQ) of an individual analytical procedure is the lowest amount of analyte in a sample that can be quantitatively determined with suitable precision and accuracy.2
Both the LOD and LOQ should be verified by a suitable number of preparations known to be prepared near the respective limit being evaluated.4 LOD and LOQ can be estimated using a signal-to-noise approach with typical values of three-to-one for LOD and 10-to-one for LOQ.
During method validation, standard solutions are prepared at the estimated LOD and LOQ (three preparations for LOD and three preparations with duplicate analyses for LOQ). Typical acceptance criteria for LOD require that the analyte be detected in each analysis. For LOQ, the percent recovery is determined for each of the six measurements and should fall between 75% and 125% recovery. The relative standard deviation is also determined for the six measurements and should be less than 25%.
Robustness–Chromatographic Conditions: The robustness of an analytical procedure is a measure of its capacity to remain unaffected by small but deliberate variations in method parameters and provides an indication of its reliability during normal usage.2
Instrument and reagent variations, for example, may be examined as part of robustness to ensure that the method provides reliable data under varying conditions. Robustness is not a critical validation component according to ICH guidelines, but should be considered on a case-by-case basis. Robustness may be determined during development of the analytical procedure, and if measurements are susceptible to variations in analytical conditions, these should be suitably controlled, or a precautionary statement should be included in the procedure.3
Stability–Stock Standard, Working Standard, Working Swab: Stability of stock standards, working standards, and working swab or rinseate samples are evaluated as part of the validation. Stability can be evaluated under various conditions such as refrigeration or protection from light, but ambient conditions are preferred. This stability period is necessary to ensure that cleaning validation samples can be collected, shipped to the testing facility, and analyzed. The length of stability is particularly important for cleaning validation sample solutions and should be at least one week old, preferably two weeks.
Table 1 lists a summary of the validation components involved in a typical cleaning validation, along with examples of typical acceptance criteria that can be set for those tests. Please note that the acceptance criteria are listed for informational examples only and that the actual acceptance criteria must be determined on a case-by-case basis, depending on validation specifics.

Cleaning validation procedures should be revalidated when the equipment train of the manufacturing process is changed.

Revalidation

Cleaning validation procedures should be revalidated when the equipment train of the manufacturing process is changed. Possible changes in the equipment train include the surface type utilized and/or surface area, which can lead to the establishment of a new MCL. A full validation can usually be avoided, and only certain elements of the cleaning validation need to be revalidated. If the new limit is within the previously established linear range, only surface recoveries (bracketing the new limit) and surface residue specificity need to be revalidated. These same two elements must be revalidated if a surface type is changed.
If the new limit is outside the previously established linear range, linearity must be extended above or below the new limit, and swab recovery, surface recovery, and surface residue specificity need to be revalidated. For a new limit below the established linear range, a new standard concentration at this level may be recommended. If the method is not linear through the new level, however, a new standard concentration is necessary. A new standard concentration requires a full revalidation.
Other possible but less likely reasons to revalidate swab recovery, surface recovery, and surface specificity include a change in the type of swab or swabbing pattern. For a change in swab type, swab specificity also needs to be revalidated. For any of the previously listed changes, elements that do not require revalidation are LOD and LOQ.
The prior revalidation discussion assumes that the validated method was for swab samples and not for rinse samples. For rinse samples, validation elements involving swabs and surfaces do not need to be conducted. Additionally, any changes in the synthesis of the drug substance, changes in the composition of the finished product, or changes in the analytical procedure require revalidation according to ICH guidance.2

There are a variety of swabs to pick from, but when a change in swab type takes place, swab specificity also needs to be revalidated.

Correction Factors

Sometimes in cleaning validation studies, it is determined that not all the residue on a surface can be fully recovered, thus producing lower recoveries. In these instances, it may be necessary to apply a recovery factor. If a recovery factor is deemed appropriate, several issues must be considered before it is set:

• Recovery factors are usually not applied if recovery results are above 70%; however, there is no standard limit.
• Recovery factors must be set under sound scientific justification.
• Recovery factors should not be used if recoveries are too low. (For example, if recoveries are consistently around 10%, a 10X factor would not be appropriate.)
• Recovery factors need to be set prior to or during validation, not during routine monitoring.
• All results used to determine the recovery factor need to be consistent and reproducible.

Recovery factors are often seen as a last resort to salvage a mediocre method. Recovery method optimization should always be explored as an alternative prior to using recovery factors.

No matter which scientific field you are in, the question of how to handle failing data during routine sample testing will arise; the world of cleaning validation is no different.

Failing Data

No matter which scientific field you are in, the question of how to handle failing data during routine sample testing will arise; the world of cleaning validation is no different. The best way to approach this issue is to address it before it becomes a problem. When developing the cleaning validation master plan or protocol, dedicate a section to appropriate handling of failing results. Here, a step-by-step investigation of the results can be laid out in advance, so that decisions won’t be made based on instance-by-instance circumstances. When reviewing data, regulatory agencies like to see that failing results were handled in a consistent and systematic manner.
All data that do not meet protocol or master plan acceptance criteria need to be treated as a deviation. They must be handled by first being verified, resolved, and approved. This may require that samples be retested. Sometimes more samples may need to be collected to verify outlying results. If results indicate that a criterion or limit is not attainable under set conditions, modifications to the method, protocol, standard operating procedure, or master plan may be entertained. Again, all of these scenarios should be investigated during the feasibility/method development/validation stage of the cleaning validation study. n
Lingenfelter, Atkins, and Evans are senior chemists in the method development and validation group at Lancaster Laboratories Inc. For more information, reach Lingenfelter at (717)656-2300, ext. 1449, or at elingenfelter@lancasterlabs.com.

References

1. Active Pharmaceutical Ingredients Committee (APIC). Cleaning validation in active pharmaceutical ingredient manufacturing plants. Washington, DC: APIC; 1999. Available at: http://apic.cefic.org/pub/4CleaningVal9909.pdf. Accessed July 10, 2009.
2. International Conference on Harmonisation (ICH). Harmonised tripartite guideline: validation of analytical procedures: text and methodology Q2(R1). Geneva, Switzerland: ICH; 2005. Available at: http://www.ich.org/LOB/media/MEDIA417.pdf. Accessed July 10, 2009.
3. United States Pharmacopeia/National Formulary. USP 32/NF 27, General Chapters: <1225>Validation of Compendial Procedures. Rockville, Md.: United States Pharmacopeial Convention; 2009.