Fate of chemicals following exposure V: Pharmacokinetics & toxicokinetics

Pharmacokinetics may be defined as the study of the dynamic movements of foreign chemicals (xenobiotics) during their passage through the body and as such encompasses the kinetics of absorption, distribution, biotransformation/metabolism, and excretion (ADME). It can simply be described as how the body handles xenobiotics. Pharmacokinetics uses mathematical equations (models) to describe the time course of ADME of xenobiotics in the body enabling us to better understand, interpret and even predict the nature and the extent of the biological effects (therapeutic or toxic) of xenobiotics. Several approaches are used in pharmacokinetics to describe the fate of xenobiotics in the body, including considering the body as one or more homogenous compartments based either on mathematical fitting of the time-course concentration data or physiological properties. Description of the rates of the movement of xenobiotics into tissue(s) allows better interpretation and prediction of the fate of xenobiotics inside the body. This chapter will introduce the reader to basic concepts and principles of pharmacokinetic analysis using both compartmental and physiologically based models.