抄録
Microdose clinical study was introduced to Japan in June 2008 for the purpose of promoting new drug development. However, the upper dose of the study is below 100 μg and the application of findings to drug development is limited. On the other hand, the ICH-M3 guidance “Non-clinical safety studies for the conduct of human clinical trials for pharmaceuticals” was revised in June 2009, which introduces other approaches to exploratory clinical studies. The guidance describes five approaches (two microdose approaches, one sub-therapeutic single dose approach, and two up to therapeutic dose range repeated-dose approaches). Because the highest doses of these studies are limited to within the anticipated non-toxic dose ranges, requirement of toxicity tests is decreased compared to the classic phase 1 study. The rationales for the reduction of toxicity tests are explained.
