ABSTRACT
The International Conference on Harmonization (ICH) E5 guideline (1998) provided a general principle for the evaluation of the impact of ethnic factors on efficacy, safety, and dosage of a new treatment. The definition of ethnicity was broad in this guideline and included intrinsic factors such as genetics, age, height, and weight, and extrinsic factors such as medical practice, diet, socioeconomic status, and environment. The guideline acknowledges that despite these differences, most drugs show comparable characteristics and effects across regions. Thus, clinical trial data developed in one region may be extrapolated to another region if a bridging study shows evidence that the drug will behave similarly across both regions in terms of pharmacokinetics (PK), efficacy, and safety. However, the application of this principle to
evaluate new treatments can be complicated. In particular, there is no commonly accepted statistical criterion for “similarity” of efficacy across regions.
