Related Experiment Video

Updated: Mar 1, 2026

Human Liver Spheroids from Peripheral Blood for Liver Disease Studies
09:51

Human Liver Spheroids from Peripheral Blood for Liver Disease Studies

Published on: January 27, 2023

2.3K

What should the clinician know about the cytochrome P450 system?

J P Benhamou1

  • 1Hôpital Beaujon, Clichy, France.

European Journal of Gastroenterology & Hepatology
|April 28, 2000
PubMed

Insights

Cytochromes P450 enzymes detoxify harmful substances in the liver. However, their metabolic processes can generate toxic byproducts, leading to liver damage through direct cellular injury or immune responses.

Area of Science:

  • Biochemistry
  • Toxicology
  • Pharmacology

Background:

  • Cytochromes P450 (CYP450) are crucial enzymes involved in xenobiotic metabolism.
  • These enzymes are primarily expressed in the liver and play a significant role in drug and toxin detoxification.
  • CYP450-mediated metabolism is essential for converting lipophilic compounds into water-soluble metabolites for excretion.

Purpose of the Study:

  • To elucidate the role of cytochromes P450 in hepatotoxicity.
  • To describe the mechanisms by which CYP450 enzymes contribute to liver injury.
  • To differentiate between metabolite-related and immune-related hepatotoxicity.

Main Methods:

  • Review of existing literature on cytochromes P450 and hepatotoxicity.
  • Analysis of biochemical pathways involved in xenobiotic metabolism.
  • Categorization of hepatotoxicity based on etiological mechanisms.

Main Results:

  • Cytochromes P450 catalyze the mono-oxidation of various substrates, including toxins and drugs.
  • Metabolism by CYP450 can produce reactive intermediates that cause direct damage to liver cells (hepatocytes).
  • These reactive metabolites can also trigger immune responses, leading to immune-mediated liver injury.

Conclusions:

  • Cytochromes P450 are key players in the development of drug-induced liver injury.
  • Hepatotoxicity mediated by CYP450 occurs through two primary pathways: direct cellular damage and immune system activation.
  • Understanding these mechanisms is vital for predicting and managing drug-induced liver toxicity.

More Related Videos

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling09:33

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling

Published on: March 20, 2018

14.4K
Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures10:44

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures

Published on: March 28, 2017

10.3K

Related Concept Videos

Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes01:28

Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes

Cytochrome P450 (CYP450) enzymes are a superfamily of heme-containing monooxygenases that play a pivotal role in Phase I drug metabolism by catalyzing oxidation and reduction reactions.These enzymes transform lipophilic xenobiotics into more hydrophilic metabolites, facilitating subsequent Phase II conjugation and eventual excretion. The CYP450 family is classified into families (e.g., CYP1–CYP3) and subfamilies (e.g., CYP2A, CYP2C), based on amino acid sequence homology.CYP450...
53
Pharmacogenetics of Drug Metabolism: Overview01:27

Pharmacogenetics of Drug Metabolism: Overview

Genetic polymorphism in drug metabolism is crucial to the inter-individual variability observed in drug responses. Drug metabolism primarily involves the chemical modification of drugs and other xenobiotics to enhance their elimination by increasing their polarity. Two main classes of enzymes mediate this biotransformation process: Phase I enzymes, primarily cytochrome P450s, catalyze oxidation and reduction reactions, while other enzymes, such as esterases, mediate hydrolysis, and Phase II...
68
Pharmacokinetics: Drug–Drug Interactions01:25

Pharmacokinetics: Drug–Drug Interactions

Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
544
Pharmacokinetics in Pediatric Patients: Drug Metabolism01:24

Pharmacokinetics in Pediatric Patients: Drug Metabolism

In pediatric care, understanding the nuances of hepatic drug metabolism is crucial, as it significantly differs from that of adults. This divergence is primarily due to the developmental stage of drug-metabolizing enzymes, which affects how medications are processed in the body. In neonates, for instance, the activity of Phase I enzymes—critical for the initial breakdown of drugs—is markedly reduced, functioning at just 20–40% of the levels seen in adults. This reduction poses...
293
Effect of Hepatic Disease on Pharmacokinetics: Drug Dosing and Hepatic Blood Flow01:26

Effect of Hepatic Disease on Pharmacokinetics: Drug Dosing and Hepatic Blood Flow

Chronic liver disease significantly impacts drug metabolism due to alterations in hepatic blood flow and enzyme accessibility. This disruption affects the body's pharmacokinetics—the movement and processing of drugs within the system. Key enzymes crucial for metabolizing medications become less accessible, changing how drugs are processed and utilized. Furthermore, liver disease influences the synthesis of plasma proteins, such as albumin and globulins, which play critical roles in drug...
302
Drug Metabolism: Phase I Reactions01:17

Drug Metabolism: Phase I Reactions

A phase I reaction is a biochemical process that introduces a functionally reactive polar group to a substance. This transformation predominantly occurs in the liver, facilitated by the cytochrome P450 system of hemoproteins situated in the lipophilic endoplasmic reticulum of cells. The metabolite generated through this process can have varying polarities. If it is sufficiently polar, it can be easily excreted in the urine due to its water compatibility. However, if the metabolite is nonpolar,...
5.3K