ABSTRACT
This chapter provides a clear example of how microdosing can be used to answer specific questions and the results used to make go/no-go decisions during drug development. Accelerator mass spectrometry (AMS) is an ultra-sensitive technique for quantitative analysis of low abundance isotopes that has found utility in very-low-level tracer analysis in biological samples using, almost exclusively. The intravenous dose level for a cross-over study is likely to be orders of magnitude higher than for a microtracer study, which can dramatically increase the resource required to develop a suitable intravenous formulation. An area of biomedical AMS that has gained considerable traction within the pharmaceutical development industry is that of concomitant clinical dosing, whereby an isotopically labeled intravenous dose of test compound and a non-labeled extravascular dose of the same compound are co-administered to the same human subject. The conduct of pediatric trials remains a challenge.
