How to Maintain Suitable Analytical Test Methods: Tools for Ensuring a Validation Continuum

Oct 01, 2005
Volume 18, Issue 10

Stephan O. Krause, Ph.D.
Many industry professionals know that analytical testing for biopharmaceuticals for all raw materials, production in-process stages, and final containers must be validated, and they generally understand how this can be achieved. Many of us even understand the basic concepts of laboratory compliance and production process quality. However, how exactly are analytical test method performance and process robustness related and how do they depend on each other? Furthermore, how do we monitor and maintain the accuracy and reliability of analytical methods long after validation completion to ensure the suitability of these methods for measuring process quality?

Most monitoring and maintenance activities should be controlled within a validation master plan (VMP) program. A good VMP in quality control (QC) should include not only detailed strategies and timelines for initial validation activities but also tools for maintaining compliance for years to come. The lifecycle of an analytical method should be captured from beginning to end. The beginning can be defined to lie somewhere between early-stage and finished method development, whereas the end is usually the replacement of one method with a better one. Currently, relatively little guidance exists for maintaining compliance and validity for analytical testing. This article focuses on how to run a practical program for analytical method maintenance (AMM) and how to ultimately integrate it into the production process. Detailed suggestions for analytical method development (AMD), analytical method validation (AMV), and analytical method transfer (AMT) as well as regulatory submissions are discussed elsewhere.1-7

Figure 1 illustrates a simplified ideal sequence of QC qualification and validation activities to bring an analytical method initially into compliance. If executed as written, a compendial method does not require AMD, but it will require test method verification, which demonstrates method suitability under the actual condition of use. The concept and data requirements for test method verification are described in the new draft chapter <1226> Verification of Compendial Procedures for the United States Pharmacopoeia (USP).8 The data requirements for compendial method verifications are similar to those required to demonstrate method comparability for each test method category (for example, quantitative limit test).7


Figure 1. Process Map for Analytical Method Validation
All compendial and non-compendial test methods should be listed in the QC VMP, together with the supporting instrumentation and equipment, computer software and hardware, critical reagents, assay standards and controls, and operator training. Although the listing of these details is time-consuming and constitutes a front-heavy planning activity, it is essential later for maintaining a compliant QC validation and testing program. All supporting test system components that are prerequisites for AMV should be identified and connected to each test method in the VMP. To be practical and effective for prioritizing, and therefore, the assignment of target completion dates, all AMV prerequisites should match the same priorities as the supported AMV. When considering timelines in preparing the overall QC VMP and all individual project plans, keep in mind that components of a validation project could fail and therefore have an associated risk to the timely completion of the overall project. Figure 1 identifies some of the prerequisites (for example, instrument qualification) that should be completed before initiating an AMV. Using Gantt charts or other similar project management tools assists in the layout of efficient sequences of validation activities and helps ensure sufficient resources and time for completion.

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