There are many ways to answer the question “do you have a validated biomarker for this compound”. Often this question cannot be answered unless you have the following information about the intended assay:

• Is this for a small molecule or a large molecule?
• What is the species? Is this the right biomarker for this species?
• What is the intra-subject and inter-subject variability?
• Is this data going to be used for a PK/PD plot or for a statistical comparison?
• Is this an endogenous biomarker? Will this biomarker be present in the matrix? Do different disease states affect the concentration of this biomarker?
• Is this biomarker present in the environment?
• Is reference material available for this biomarker?
• What is the cost you are willing to spend for this assay?

Since the tobacco industry has moved into the area of regulated bioanalysis, we have noted that there is confusion surrounding the regulatory standards required for analytical methods to be used for testing biomarkers in biofluids. This presentation will focus on demonstrating the benefits of using a fit-for-purpose approach concerning the validation of biomarkers. In conclusion a properly constructed and validated Bioanalytical Tobacco Assay (BTA) that has the appropriate selectivity, sensitivity and improved analytical precision has a direct impact upon statistical analysis of the study. Specifically, these parameters will have a direct impact upon the number of subjects that you have to dose in order to achieve the same statistical power.