Juvenile animal testing in drug development--is it useful?

In pharmaceutical drug development, there has been increased interest in the need to perform juvenile animal studies to support the safety of use of new medicines in the pediatric population. Although such studies are not new, the increased interest has been "formalized" in recent regulatory guidelines. As a result, companies are now performing many more studies in juvenile animals, even when there is a lack of robust knowledge of cross-species functional and kinetic differences among juveniles that means extrapolation of any toxicology study finding to an immature human may not be easy or even relevant, especially if performed in the wrong species at the wrong time. It will be shown by presentation of some basic considerations needed in order to perform such testing, that juvenile animal studies are indeed feasible. However, it will also be highlighted that (based on available knowledge) there are currently not enough clear-cut examples to answer the question of whether juvenile animal toxicology studies to support pediatric development (by affecting the performance or design of a pediatric clinical trial or identifying a potential different-from-adult safety risk in clinical use) are truly useful or necessary.