In today’s small blog article, we will learn about bioanalytical method validation and its recent advancements. Bioanalytical method validation refers to validation of analytical methods that deal with analysis of an analyte in biological matrices (like urine, saliva, blood etc.). Validation of such methods for the quantitative determination of analytes (e.g. drugs under development or their metabolites) and biomarkers in a given bio-matrix are critical for the successful conduct of nonclinical and clinical pharmacology studies. Validated methods provide critical information to support the safety and potency of drugs. Validating the analytical method provides us with results that can be trusted. Validation of bioanalytical methods answers 4 major questions:
- Through specificity / selectivity, it evaluates if the method serves the intended purpose of analysing exactly the analyte under question. If so, does it face any interference from any other components?
- With the accuracy and precision parameters, it answers the variabilities associated with the obtained datasets, thus questioning how much error can be expected and is allowed to be tolerated.
- By determining the range, it defines an upper and lower limit within which the method will perform reliably.
- Obtaining stability data, it establishes the effect of wrong handling or storage of sample on processing reliable data using the particular method.
Unfortunately, unlike validation of analytical methods [see the corresponding guideline “ICH Q2(R1)”], validation of bioanalytical methods is still not harmonized. Different countries have their own guidelines developed by their respective regulatory bodies like the US FDA (United States Food and Drug Administration), EU EMA (European Medicine Agency), Brazil ANVISA (National Health Surveillance Agency), Japan MHLW (Ministry of Health, Labour, and Welfare) to name just a few; that requires companies to follow their specific requirements when intending to launch drug products on that markets. A good overview can be found in this article, although the FDA has recently (in May 2018) published their new guideline, which was of course not yet included in that paper.
The US FDA, over the years, has extended the scope of validating specific bioanalytical methods (GC, HPLC) in selected biological matrices to biomarker concentration evaluation and now to ligand binding assays (LBA). The EMA, in its guideline, has not included the quantitative determination of biomarkers in assessing pharmacodynamic endpoints. ANVISA guideline is limited to chromatographic techniques in combination with mass spectrophotometry for quantitative analysis of drugs in selective biological matrices. Unlike other regulatory bodies, it has however, extended the range of biomatrices. MHLW follows two separate guidelines for large and small molecular weight drugs respectively and are not limited to selected analytical methods or detection systems.
Although these guidelines are quite different, the main validation parameters to be evaluated are still the same, such as accuracy, precision, specificity/selectivity, linearity, sensitivity and stability as well as often recovery, robustness and reproducibility aspects also needs to be checked. Interestingly, the method performance (e.g. how many replicates or which samples) and acceptance criteria (e.g. RSD ± 15%) for these validation parameters are in some points quite similar, while in others they are varying a lot. So how to behave when you are a pharmaceutical company planning to launch your product on different markets? Imagine to launch at two markets (Brazil and Europe), do you have to follow the requirements of both authorities or do you “just” have to follow the stricter ones? E.g. for intra-precision (repeatability) the Brazilian ANVISA guideline RDC 27/2012 requires 5 replicates in at least 5 concentrations, while the EMA just requires 5 samples at 3 concentrations and at LLOQ (lower limit of quantification) … Thus, a regulatory strategy should be set up before planning to start any validation experiments.
To summarize, unlike analytical methods, bioanalytical methods validation guidelines are not yet harmonized. Although recent development in the field of harmonization has already been started, it is still not put into practice, as the ICH is planning to issue the M10 bioanalytical validation guideline in June 2020. The major regulators have issued their respective guidelines regarding specific analytical methods to be used for particular drugs in specific biological matrices. The validation parameters remain mostly the same for all with certain differences about the class of compounds for which the guidelines to be applied and their performance as well as acceptance criteria.