Adding value through accelerator mass spectrometry-enabled first in human studies.

Accelerator mass spectrometry (AMS) is an ultra-sensitive technique for the analysis of radiocarbon. It is applicable to bioanalysis of any C-labelled analyte and any sample type. The increasing body of data generated using LC+AMS indicates that the methodology is robust and reliable, and capable of meeting the same validation criteria as conventional bioanalytical techniques. Because it is a tracer technique, AMS is capable of discriminating between an administered radiolabelled dose and endogenous compound or non-radiolabelled compound administered separately. This paper discusses how it can be used to enhance the design of first in human (FIH) clinical studies and generate significant additional data, including: fundamental pharmacokinetics (CL and V), absolute bioavailability, mass balance, routes and rates of excretion, metabolic fate (including first-pass metabolism, identification of biliary metabolites and quantitative data to address metabolite safety testing issues), and tissue disposition of parent compound and metabolites. Because the C-labelled microtracer dose is administered at the same time as a pharmacologically relevant non-radiolabelled dose, there is no concern about dose-linearity. However the mass of the microtracer dose itself is negligible and therefore does not affect the outcome of the FIH study. The addition of microtracer doses to a FIH study typically requires little additional expense, apart from the AMS analytics, making the approach cost-effective. It can also save significant time, compared to conventional approaches, and, by providing reliable human in vivo data as early as possible, prevent unnecessary expenditure later in drug development.