ABSTRACT
Biotransformation plays a key role in toxicity and carcinogenicity. It is not a “detoxification” process, but a mechanism for converting poorly excretable lipophilic xenobiotics to readily excretable water-soluble compounds. Research monographs devoted to the general principles of xenobiotic biotransformation include those of W. B. Jakoby, Jakoby et al., J. Caldwell and G. D. Paulson, and J. W. Gorrod et al. P450 activities are sex-, tissue-, and age-dependent and differentially regulated at the constitutive level and in response to xenobiotic exposure and endogenous mediators such as hormones. Allelic variation in the genes coding for the inducer receptor as well as for the putative repressor protein are believed to result in polymorphic variation in both constitutive activities and response to induction and determine individual susceptibility to toxicity and carcinogenicity to drugs and xenobiotics biotransformed by these proteins. The primary type of sulfotransferase involved in xenobiotic biotransformation is that reacting with aryl compounds.
