Validation bioanalytical application

Given the foregoing discussion of some of the unique characteristics of macromolecules that lead to clear differences in their pharmacokinetics compared to those typical of small-molecule drugs, there is a subset of the entire group of bioanalytical assay validation parameters that are of key importance in support of pharmacokinetics of candidate macromolecular therapeutics. Assuming demonstration of accuracy and precision of sufficient quality for the intended application of the assay (e.g., non-GLP discovery support or GLP toxicokinetic support, as discussed above), the most important characteristics of a given assay in support of pharmacokinetic studies are likely to be selectivity, specificity, and reproducibility for analysis of incurred samples. These are all related to the ability of the LBA to detect and quantitate solely, or as closely as possible to solely, the analyte of interest. 

Sample preparation techniques must be chosen and optimized with careful regard to the method purpose. As stated in the ICH guidelines, the validated method must be appropriate for the intended purposes. Sample preparation procedures used in bioanalytical applications and their important features are described in Table 4.1. An appropriate technique should be chosen with regard to extraction time, selectivity, the number of steps, solvent consumption, and the possibility of using on-line techniques. 

Simpson Jr., S.L. Qurrino, J.P. Terabe, S. On-line sample preconcentration in capillary electrophoresis. Fundamentals and applications. J. Chromatogr. A, 2008,1184, 504—541. Mayer, B.X. How to increase precision in capillary electrophoresis. J. Chromatogr. A, 2001, 907, 21-37. http //www.fda.gov/cder/guidance/4252fiil.htm. Guidance for industry. Bioanalytical method validation (accessed November 2008). 

Additional discussion of the various types of stabdity data that are typically generated in support of validation smdies is given here, and also for the special case of bioanalytical applications in Section 10.4.1. 

European Medicines Agency (EMA) Guideline on Bioanalytical Method Validation [33] Guidance for methods used in pharmacokinetic studies and filed in pharmaceutical applications in the EU... 

The fundamental parameters for bioanalytical validations include accuracy, precision, selectivity, sensitivity, reproducibility, stability of the drug in the matrix under study storage conditions, range, recovery, and response function (see Section 8.2.1). These parameters are also applicable to microbiological and ligand-binding assays. However, these assays possess some unique characteristics that should be considered during method validation, such as selectivity and quantification issues. 

Biotech macromolecule drugs are chemically and biologically different from the small-molecule drugs. Special considerations must be given for bioanalytical method development, validation and applications, including the purity of the re-... 

As for any bioanalytical method, the extent of validation for an immunoassay should be related to the intended application of the assay. Thus, if an immunoassay is intended to support rapid screening in discovery R D, the characterization of specificity and the accuracy and precision specifications may be less stringent than if the assay is used to support pre-clinical and clinical development studies. Indeed, an assay for discovery support may be designed to detect active metabolites as well as parent molecule, so that... 

This chapter describes the challenges and practical approaches to ligand-binding assays for biomarker quantification. The main points include (1) defining the purpose of the bioanalytical method application, (2) assay development using the appropriate reagents, (3) assay qualification and validation meeting the intended purpose of an assay, and (4) statistical treatments and interpretation. 

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