Efficacy and side-effects should be closely looked for and, if appropriate, plasma levels should be monitored, eg phenytoin, phenobarbitone. In children, the liver is up to 50 per cent greater as a percentage of total body weight than in adults. Once the hepatic pathways are mature, an increased metabolic rate may be seen and higher doses required. The kidneys are relatively immature at birth, and both glomerular filtration rate and tubular secretion are poorly developed. Neonates and infants therefore have a reduced ability to eliminate drugs renally and need dose reductions.
Maturity is reached by eight months.
The number of drugs prescribed for children is very small, especially if one only considers those licensed for use in children. Drug research usually takes place primarily in the adult population, with little or no research being done in children. If only licensed drugs for licensed indications were used, many children would be deprived of valuable therapeutic treatment. Joint Medicines Committee are looking to resolve these issues and produce national guidelines for prescribing in children. Doses Age bands are often used for licensed products with large therapeutic indices.