The pharmacokinetics of a compound is dependent upon its physicochemical properties, intrinsic clearance, and apparent volume of distribution, as well as its interaction with various tissue types. As well as determining safety and efficacy, pharmacokinetic studies serve as a means of describing comparisons between the disposition of formulations and can be used as the basis for tailoring the compound to another dosing regimen. The wide variety of structures of natural products result in a number of metabolic routes and detoxification mechanisms. The mathematical principles are presented graphically. Finally, drug interactions, particularly involving cytochrome P450 inhibition or enhancement, are discussed.