Metabolites in safety testing: metabolite identification strategies in discovery and development

The publication of the FDA MIST guidelines in 2008, together with the acknowledged importance of metabolism data for the progression of novel compounds through drug discovery and drug development, has resulted in a renewed focus on the metabolite identification strategies utilised throughout the pharmaceutical industry. With the plethora of existing and emerging technologies available to the metabolite identification scientist, it is argued that increased diligence should be applied to metabolism studies in the early stages of both drug discovery and drug development, in order to more routinely impact chemical design and to comply with the concepts of the MIST guidance without re-positioning the definitive radiolabelled studies from there typical place in late development.Furthermore, these strategic elements should be augmented by a broad and thorough understanding of the impact of the derived metabolism data, most notably considerations of absolute abundance, structure and pharmacological activity, such that they can be put into proper context as part of a holistic safety strategy.The combination of these approaches should ensure a metabolite identification strategy that successfully applies the principles of the MIST guidance throughout the discovery/development continuum and thereby provides appropriate confidence in support of human safety.