Compared to adults, children's growth and developmental changes cause marked pharmacodynamic and pharmacokinetic differences to the way they respond to medicines.
The most common pharmacodynamic differences concern adverse reactions that have occurred especially with such severe side effects that are not known in adults. Due to their smaller size, children need smaller dosages of medicine than adults. Depending on a child's developmental phase, he or she may, however, need a relatively (e.g. in relation to weight) smaller (newborns) or larger (preschoolers) dosage. Children and adolescents also have illnesses that adults do not. Experience has shown that without clinical trials children cannot receive the health benefits brought on by the development of medicines.
Special Features and Problems of Children's Medicines
Currently children's illnesses cannot be treated, with respect to their needs, with such a vast selection of licensed medicines as adults' illnesses.
The research, development and use of medicinal products for children have, until now, significantly fallen behind that of adults' medicinal products. Due to the relatively small markets and expensive development and research costs, children's medicines have generally not fulfilled the high profit expectations of the pharmaceutical industry.
Several studies have shown that over 50% of the medicines used to treat children are either unlicensed (e.g. products produced by hospitals' own pharmacies) or prescribed off label (regarding e.g. route of administration) opposed to what the use of the medicine in question was officially authorized for (i.e. based on grounds of evidence).
The situation is far from ideal as:
Children have to be prescribed unsuitable forms of medicines.
Medicines meant for adults may contain unsuitable or even harmful supplements, preservatives, additives or solvents (e.g. alcohol).
The risk of adverse reactions is increased if there is no research based information about the right dosage, or if the formulation of the medicine makes it difficult to administer small dosages accurately.
The risk of insufficient treatment or the possibility of receiving ineffective treatment is increased if there is no research based information about the right dosage, or the formulation of the medicine makes the administration of the correct dosage difficult.