Emerging technologies, recent developments, and novel applications for drug metabolite identification.

Drug metabolite identification and metabolic characteristics analysis play a crucial role in new drug research and development, because they can lead to varied efficacy, severe adverse reactions, and even toxicity. Classical methodologies for metabolite identification have mainly been based on mass spectrometry (MS) coupled with gas chromatography (GC) or liquid chromatography (LC), and some other techniques are used as complementary approaches, such as nuclear magnetic resonance (NMR). Over the past decade, more and more newly emerging techniques or technologies have been applied to metabolite identification, and are making the procedure easier and more robust, such as LC-NMR-MS, ion mobility MS, ambient ionization techniques, and imaging MS. A novel application of drug metabolite identification based on "omics" known as pharmacometabonomics is discussed, which is an interdisciplinary field that combines pre-dose metabolite profiling and chemometrics methods for data analysis and modeling, aiming to predict the responses of individuals to drugs.