Models of pharmacokinetics in the treatment of acute postoperative pain in paediatrics

Abstract

The development of new, sensitive techniques for assaying drugs and drug metabolites together with progress in computer technology have made possible remarkable advances in pharmacokinetics studies. Pharmacokinetics is the mathematical description of drug disposition over time. In other words, it is what the body does to the drug over time. Pharmacokinetics deals with the fate of the drugs in the body, including the mechanisms and kinetics of drug absorption, distribution, elimination (excretion and metabolism), and transport to the site of action (biophase). The latter process can be considered as a link between pharmacokinetics and pharmacodynamics; fundamentally, however, it is a pharmacokinetic process. The volume of pharmacokinetic drug evaluations in children falls considerably behind that performed in the adult population, with the exception of a few limited areas. There are some appropriate reasons for the limited availability of pharmacokinetics data in children. The thalidomide tragedy led to more stringent regulations. Consequently, manufacturers began omitting drug studies in infants and children, creating a population of “therapeutic orphans”. Performing research in children is not only problematic for ethical reasons but also due to logistic difficulties. Patient and parent cooperation may be poor and phlebotomy is typically more difficult to perform in children. Limited patient populations present a problem even in large centers.