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Influence of xenobiotics on drug metabolism and its sensitive detection
1Friedrich Schiller University, Institute of Pharmacology and Toxicology, Jena, GDR.
Abstract:
Biotransformation of drugs and other xenobiotics in the liver plays an important role intoxication and detoxication processes, i.e. changes in biotransformation activity have significant biological consequences. For that reason the determination of biotransformation activity is useful. The rate of some biotransformation reactions can be markedly changed by very small doses of xenobiotics. These changes may be used for the sensitive detection of the exposure to xenobiotics. Among biotransformation reactions cytochrome P-450-dependent monooxygenation is very important. It can be induced and inhibited by xenobiotics. Induction of P-450 forms can be detected by various methods, e.g. by using model reactions. Ethoxycoumarin O-deethylation, ethoxyresorufin O-deethylation, pentoxyresorufin O-depentylation and ethylmorphine N-demethylation are catalyzed at different P-450 forms, and their determination is described in detail.
Insights
Measuring liver biotransformation activity, particularly cytochrome P-450 enzyme function, is crucial for detecting xenobiotic exposure. Specific model reactions offer sensitive methods for assessing these changes.
Area of Science:
- Pharmacology
- Toxicology
- Biochemistry
Background:
- Liver biotransformation of xenobiotics is critical for detoxification and preventing intoxication.
- Changes in biotransformation activity have significant biological implications.
- Xenobiotics can alter biotransformation rates, even at low doses, enabling sensitive exposure detection.
Purpose of the Study:
- To highlight the importance of determining biotransformation activity.
- To introduce sensitive detection methods for xenobiotic exposure.
- To detail methods for assessing cytochrome P-450 induction.
Main Methods:
- Utilizing model reactions to detect induction of cytochrome P-450 (CYP) forms.
- Measuring ethoxycoumarin O-deethylation.
- Measuring ethoxyresorufin O-deethylation, pentoxyresorufin O-depentylation, and ethylmorphine N-demethylation.
Main Results:
- Specific model reactions are sensitive indicators of xenobiotic exposure.
- Different P-450 isoforms can be selectively assessed using these reactions.
- Detailed procedures for determining these biotransformation activities are provided.
Conclusions:
- Determination of biotransformation activity is biologically significant.
- Model reactions provide a sensitive approach for detecting xenobiotic exposure.
- Cytochrome P-450 induction can be reliably detected using these methods.