Editorial Lévesque & Lachance
in matrix) [2] performed with at least three separate aliquots instead of analyzing at least three replicates as many CROs do. This practice makes sense from a scien- tific point of view, but will the other agencies apply this requirement? We should consider that the previous sta- bility data are still valuable, but can be completed with some testing.
Other deficiencies related to old method developments The agencies are continuously improving the way they apply the guidances and the way they judge the sci- ence around the method development and validation, which allows us to constantly improve our processes as well as the robustness of our methods. Stabilities, metabolites conversions, matrix effect, bioanalytical range utilization, investigations on specific situations – all of these have pushed the CROs to improve their science and processes during the last decades. It is easy to see the evolution and improvement of the bio- analytical method development, as well as the sample analysis process, when we compare an assay that was validated 20 years ago to a recently validated assay. In light of this, what to do with the developments done before? How can one make sure that a clinical trial performed one to two decades ago can still be submitted in 2015? At that time, the scientific knowl- edge was not there, for example, the metabolite con- version was not investigated as we currently do now. The evolution of the knowledge, as well as the agency requirements, is a real positive improvement in the submission of more reliable results. It is acknowledged that the old methods are still
good; however, adjustments or verifications should be done before use. At the least, minor adjustments should be required to bring them up to date to meet the current regulations, and in some cases, even a full re-validation may be the only option. For instance, stable isotope- labeled internal standards were not frequently used at that time. It is advisable to modify old assays by using a more suitable internal standard. It is certainly more ethical not to re-dose a study to
change the reference medication. However, what about using old data? We can save studies when ISR was not performed as published [3], but what about the other parameters that have changed in previous years? It is feasible in some cases, but it needs to be a case-by-case evaluation.
Other regulations requirements to pay attention to Conversion/back-conversion of metabolites Throughout the last few decades, we saw that the agen- cies were increasingly concerned about the conversion
Bioanalysis (2016)
of metabolites that could cause an overestimation of the drug concentration. This is still of concern by the regulatory agencies even if the CROs have imple- mented processes that will evaluate the potential con- version of metabolites during method development and validation. The laboratories should make sure the experiments carried out are appropriate to the mole- cules and the matrices. For example, we saw that the way a powder is solubilized and the way a solution used for the testing is prepared can affect the test results and the conclusions could be wrong. We always need to be on the lookout for any sign of conversion, for example:
• to constantly monitor the ISR results and varia- tions, particularly when a trend can be observed;
• to verify the pre-dose sample concentrations, the zero samples;
• to monitor any trends with the internal standard response;
• to carefully study the incurred sample chromatograms.
Matrix effect Another hot topic in 2015 was the way the matrix effect should be measured or calculated. We cer- tainly need to pay attention to the way it is tested, as the test design could say what we want to see, not the real situation happening in the analysis tube. The matrix effect test as requested by most of the agencies requires evaluating only the ion suppression in differ- ent matrix lots including hemolized and hyperlipemic matrix. This procedure does not verify the impact of different matrix lots on the extraction recovery and efficiency. And we can also speak about the matrix used to verify the matrix effect. As published [4], it can always be selected according to the purpose of the analysis. Specific population study may require verifi- cation of the matrix effect using these special popula- tion matrices. Recently, an agency requested to verify the matrix effect on charcoal stripped matrix (used to prepare calibration standards) for an assay used to determine an endogenous compound. They also asked for the impact of hemolyzed and hyperlipemic stripped matrix on matrix effect. It is acknowledged that once stripped, each matrix lot will be similar in terms of content. Moreover, only normal matrix will be used for the preparation of calibration standards.
Sample handling stability Sample handling stability is really important to test but not enough CROs still test it. In addition, the regulations are not clear on this important step of
future science group
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