ABSTRACT
This chapter seeks to introduce the basic concepts of pharmacokinetics and describeS the practices in the conduct of studies. The Food and Drug Administration believes that data from studies on the absorption, distribution, metabolism, and excretion of a chemical provide insight into mechanisms of toxicity and are essential in the design and evaluation of results from other toxicity studies. Absorption describes the process by which a chemical crosses a barrier, typically a biological membrane, to gain access to the inner complexities of an organism. Systemic absorption of inhaled materials is highly dependent on the physical properties of the inhaled materials, which dictate how easily the materials reach the alveoli of the deep lung. The absorption of a chemical into the skin is a function of the nature of the molecule, the behavior of the vehicle, and the status of the skin. The progress and products of biotechnology have brought some new challenges to the assessment of pharmacokinetics and toxicokinetics.
