With the advent of pediatric exclusivity, and requirements to conduct clinical studies in children, an emphasis has been placed on finding a safe and efficacious dose of a drug in children. Children are not 'small adults', and drug dosing in this population requires special consideration. There are subtle physiological and biochemical differences among neonates, infants, children, adolescents and adults and dosing in pediatrics requires proper understanding of these factors. Furthermore, dosing in children, as in adults, should be based on pharmacokinetic and pharmacodynamic data. This is an evolving area, as pediatric pharmacokinetic studies are becoming mandatory for getting approval of new drugs in this population.