Factors Affecting Metabolism and Disposition

In the preceding two chapters, the disposition and metabolism of foreign compounds, as determinants of their toxic responses, were discussed. In this chapter, the influence of various chemical and biological factors on these determinants will be considered. 

External factors such as the dose of the compound or the manner in which it is given, the diet of the animal, and other foreign compounds to which it is exposed are also important for the eventual toxic response. Although some of these factors may be controlled in experimental animals, in the human population they remain and may be extremely important. 

For a logical use of experimental animals as models for man in toxicity testing, these factors must be appreciated and used for the fullest possible exploration of potential toxicity. 

The factors affecting the disposition and toxicity of a foreign compound may be divided into chemical and biological factors. 

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Factors affecting metabolism and disposition of drugs or xenobiotics in vivo have been amply described elsewhere (Timbrell, 1991). They may be divided into biological factors and molecular factors. 

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