Biochemical Aspects of Toxicology

Biochemical toxicology is concerned with the mechanisms underlying toxicity, particularly the events at the molecular level and the factors, which determine and affect toxicity. 

The interaction of a foreign compound with a biological system is twofold there is the effect of the organism on the compound and the effect of the compound on the organism. 

It is necessary to appreciate both for a mechanistic view of toxicology. The first of these includes the absorption, distribution, metabolism, and excretion of xenobiotics, which are all factors of importance in the toxic process and which have a biochemical basis in many instances. The mode of action of toxic compounds in the interaction with cellular components, and at the molecular level with structural proteins and other macromolecules, enzymes, and receptors, and the types of toxic response produced are included in the second category of interaction. However, a biological system is a dynamic one, and therefore a series of events may follow the initial response. For instance, a toxic compound may cause liver or kidney damage and thereby limit its own metabolism or excretion. 

The anatomy and physiology of the organism affect all the types of interaction given above, as can the site of exposure and entry of the foreign compound into the organism. Thus, 

The distribution of a foreign compound and its rate of entry determine the concentration at a particular site and the number and types of cells exposed. The plasma concentration depends on many factors, not least of which is the metabolic activity of the particular organism. This metabolism may be a major factor in determining toxicity, as the compound may be more or less toxic than its metabolites. 

---