So, is your assay fit for the job ?
Validated analytical test methods are required by good manufacturing practice (GMP) regulations for products that have been authorized for sale and almost certainly for late-stage trial clinical material.3 Also, some methods used during the pre-clinical phase of drug development under good laboratory practice (GLP) regulations may also require validation.4However, during the development of biopharmaceuticals, methods may be employed that may not need full validation — for example, those used only for process validation or comparability studies. The various terms applied to the "not-quite-validation" of such methods include "test characterization," "qualified method," and "validated for Phase I." Considerable confusion has arisen over this topic, which has been the subject of several articles and numerous presentations at conferences. This article also seeks to explain and clarify the situation.
In basic terms, a suitable method must be based on firm scientific principles; capable of providing the necessary sensitivity, accuracy, precision, etc.; and capable of generating reliable results. During test development, we learn more about the ability of a test to meet these requirements, and we decide whether the test is going to meet suitability standards. The key questions to be answered are:
The final "full" validation of a method, especially a biological assay, requires assembly of a significant amount of data on the test's performance, so that the results produced can be subjected to statistical analysis and the variability of the results documented. This can be an expensive, time-consuming procedure, and one would not want to go through the process until it was absolutely necessary.
Regulatory Requirements and Guidelines