Evaluation of preparative high performance liquid chromatography and cryoprobe-nuclear magnetic resonance spectroscopy for the early quantitative estimation of drug metabolites in human plasma.

Definitive information on the metabolism of a drug candidate in humans is achieved through dosing radiolabelled drug as part of a clinical study, and is typically conducted post-proof of concept in Phase III of the clinical development plan. Here we describe a novel approach, using preparative high performance liquid chromatography and cryoprobe-nuclear magnetic resonance spectroscopy, to determine the human systemic exposure to a drug and its metabolites using samples derived from Phase I clinical studies. Using the described methodology, novel human plasma metabolites, as low as 10 ng/ml can be detected and quantified. This provides an opportunity, early in the development process to understand the potential role of metabolites in the safety and efficacy of drugs in humans.