Abstract
Following the publication of the guidance information for clinical studies, it is increasingly important to create an environment conductive to the implementation of microdosing clinical trials. It is known that the accelerator mass spectrometry method using radiolabeled compounds is advantageous over liquid chromatograph/mass spectrometry/mass spectrometry method in detecting and determining Japanese-specific metabolites. However to date, no pharmacokinetic study using radiolabeled compounds has been conducted for drug development in Japan probably due to a resistance in the use of radioactive substances. It is important to demonstrate the safety of the administration of a small dose of radiolabeled compound. When a microdosing clinical trial is conducted as a first in a human trial in drug development, the principal investigator and the deliberators in the Institutional Review Board (Ethics Committee) should be cautious from both the scientific and ethical viewpoints.
