ABSTRACT
The concept of quantitative extrapolation encompasses various fundamental areas of PK/TK analyses. Quantitative extrapolations are used commonly in different areas of contemporary research and evaluations; for example, environmental health sciences, drug discovery, and development and regulatory decisions, to name a few. The discipline of toxicology and the eld of drug discovery and development can be considered sciences of extrapolation. Both subjects rely on the information and knowledge obtained from cell culture, in vitro systems, experimental animals, and a relatively small number of humans. Even when there are dissimilarities, it is assumed that the non-human systems can reasonably predict a better understanding of safety considerations in humans. The knowledge gained from extrapolation of PK/TK or PD/TD data, in general, are used to improve the understanding of xenobiotics behavior in the body and the assessment of their risk for human. Predictions of the in vivo PK/TK characteristics of xenobiotics from in vitro studies is another important qualitative and often quantitative extrapolation, which are carried out on a routine basis.
