Juvenile Toxicology

Juvenile toxicology encompasses the design, conduct, evaluation, and interpretation of studies conducted in juvenile laboratory animals with the goal of assessing the safety of pharmaceuticals or environmental chemicals on the human pediatric population. Juvenile animal studies come with unique challenges that are not encountered in general toxicity studies using mature animals, including logistics of using fragile young animals, confounding factors of xenobiotics on growth and development, constantly changing histologic appearance, variations in developmental temporal windows of organ systems within and between species, and the identification of the ideal exposure timeframe that will favor translational relevance to humans. Because of these arrays of considerations, juvenile toxicology has given rise to a special area of expertise among toxicologists, laboratory animal technicians, and pathologists. This chapter briefly covers the history of juvenile toxicology and outlines the pertinent regulations set forth by the US and European agencies. The various types of study designs that may be considered juvenile toxicology studies are classified and detailed. Furthermore, an overview of the main developmental stages and features of different organ systems is presented to highlight the physiological differences that exist between young and adult individuals and their impact on drug pharmacokinetics. Examples of juvenile animal studies that led to the discovery of unique toxicity data that profited the pediatric population are also provided. Overall, this chapter offers an overview of the various considerations, challenges, and opportunities that are unique to juvenile toxicology, a field that will undoubtedly become more mainstream in drug safety assessment.