Differences in response to medical products have been observed in racially and ethnically distinct subgroups of the US population. Approved doses and dosing regimens for some of the most widely prescribed drugs have also been shown to be different in different countries (e.g., the United States, the United Kingdom, and Japan). These differences may be attributable to intrinsic ethnic factors (e.g., genetics, metabolism, race), extrinsic ethnic factors associated with environment and culture (e.g., medical practice, diet, use of alcohol, concomitant drug use, regulatory environment), or interactions between these factors.

To have truly individualized patient therapy, it is critical to evaluate the impact of these factors in global drug development, regulatory review, and clinical practice. This issue examines scientific, regulatory, and ethical considerations related to ethnic factors. Recent development of genomic tools has taken us closer to reaching individualized therapy. Several articles in this issue consider how patient factors, including genetic information, may affect the outcome of warfarin treatment. Image of James Watson from Wikimedia Commons. Craig Venter’s photo reprinted with permission from the J. Craig Venter Institute. Remaining images from iStockphoto. Cover designed by Erin Boyle.