In the young toddler and prepubertal child, the phase may be very short relative to the phase, and its contribution to overall elimination and to dosage computations may not be significant. Similarly, drugs given to the newborn usually have an extremely prolonged phase relative to the phase. Thus, for purposes of dose calculations, the newborn's entire body could be considered as a single compartment. For most drugs that follow first-order kinetics, dose adjustments can be based on plasma drug concentration, which at steady state is proportional to dose. However, the prolonged elimination of drugs in the first few weeks of life warrants substantially lower maintenance doses given at longer intervals to prevent toxicity.
Monitoring is also useful in assessing compliance.
These are dictated by clinical needs and circumstances. In the sick premature newborn, almost all drugs are administered intravenously, since GI function and therefore drug absorption are impaired and the intramuscular route is precluded because these newborns have very poor muscle mass. In older preterm newborns, full-term newborns, and older children, the oral route is used predominantly. For the acutely ill child and for children with vomiting, diarrhea, and impaired GI function, the parenteral route is recommended. All rights reserved.