It has been well established that children are not small adults but rather a distinct and heterogeneous patient group with regard to pharmacotherapy. They often exhibit a different response to both active substance and excipients. Children present a continuum of growth and developmental phases as a result of their rapid growth, maturation of the body composition, and physiologic and cognitive changes during childhood. Children differ from adults in many aspects of pharmacokinetics and pharmacodynamics, potential routes of administration, medicine-related toxicity, and taste preferences. Thus, specific dosing guidelines and useful dosage forms for pediatric patients need to be developed in order to optimize therapeutic efficacy and limit, or prevent, serious adverse side effects.