Microdosing for early biokinetic studies in humans.

Microdosing is a new concept in drug development that--if implemented in the pharmaceutical industry--would mean that new drugs can be tested earlier in humans than done today. The human microdosing concept--or 'Phase 0'--may offer improved candidate selection, reduced failure rates in the drug development line and a reduction in the use of laboratory animals in early drug development, factors which will help to speed up drug development and also reduce the costs. Microdosing utilises sub-pharmacological amounts of the substance to open opportunities for early studies in man. Three technologies are used for microdosing: accelerator mass spectrometry (AMS), positron emission tomography and liquid chromatography-tandem mass spectrometry. This paper focuses on the principle of AMS and discusses the current status of microdosing with AMS.