• consistency;
  • ethnic factors;
  • dose–response relationship;
  • ICH-E5 guideline;
  • pharmacokinetic data


The multi-regional clinical trials (MRCTs) being administered in different regions of the world now play a major role in providing evidence for the efficacy and safety of new drugs amidst the simultaneous global development and worldwide registration of such drugs, in support of the expeditious availability of medical products to patients. However, such trials present considerable challenges as far as quality, design, implementation, analysis, and interpretation are concerned. In this article, we share our observations and lessons learned from the design, implementation, analysis, and interpretation of some MRCTs with case examples. Current Japanese regulatory guidance on MRCTs is introduced along with some suggestions for design, implementation, and interpretation. Copyright © 2010 John Wiley & Sons, Ltd.