Related Experiment Video

Updated: Jul 2, 2026

Methods Development for Blood Borne Macrophage Carriage of Nanoformulated Antiretroviral Drugs
18:46

Methods Development for Blood Borne Macrophage Carriage of Nanoformulated Antiretroviral Drugs

Published on: December 9, 2010

Demonstration of the metabolic pathway responsible for nevirapine-induced skin rash

Jie Chen1, Baskar M Mannargudi, Ling Xu

  • 1Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.

Chemical Research in Toxicology
|August 30, 2008
PubMed

Insights

The 12-hydroxylation pathway of nevirapine (NVP) causes skin rashes in rats. This study identifies the specific metabolic route responsible for NVP-induced skin reactions, offering insights into drug toxicity.

Area of Science:

  • Pharmacology
  • Toxicology
  • Drug Metabolism

Background:

  • Nevirapine (NVP), a reverse transcriptase inhibitor, is known to cause adverse skin reactions and hepatotoxicity.
  • The precise metabolic pathway leading to NVP-induced skin rash has not been clearly identified.
  • Understanding the mechanism of idiosyncratic drug reactions is crucial for patient safety.

Purpose of the Study:

  • To determine whether the parent drug nevirapine or a reactive metabolite is responsible for NVP-induced skin rash.
  • To identify the specific metabolic pathway involved in the NVP skin rash using a rat model.
  • To elucidate the mechanism of NVP-induced toxicity.

Main Methods:

  • Utilized a rat model to investigate nevirapine (NVP) metabolism and associated skin reactions.
  • Manipulated metabolic pathways and tested NVP analogues, including a deuterated version to inhibit 12-hydroxylation.
  • Administered NVP and analogues, monitored blood levels, and assessed rash incidence.
  • Investigated the role of P450 enzymes and potential reactive intermediates like quinone methides.

Main Results:

  • The 12-hydroxylation pathway was identified as the primary route responsible for NVP-induced skin rash.
  • Treatment with 12-hydroxy-NVP (12-OH-NVP) induced skin rash, while a deuterated analogue showed reduced rash incidence.
  • Unexpectedly low blood levels of the deuterated analogue were observed, linked to the formation of a reactive quinone methide intermediate that inactivates P450.

Conclusions:

  • The 12-hydroxy pathway is definitively responsible for nevirapine-induced skin rash.
  • Proposed that NVP hepatotoxicity in humans involves a quinone methide formed in the liver, while skin rash may involve a quinone methide formed in the skin.
  • This study provides the first animal model of an idiosyncratic drug reaction to pinpoint the responsible metabolic pathway.

More Related Videos

Quantitative Structure-Activity Relationship, Activity Prediction, and Molecular Dynamics of Non-nucleotide Reverse Transcriptase Inhibitors10:29

Quantitative Structure-Activity Relationship, Activity Prediction, and Molecular Dynamics of Non-nucleotide Reverse Transcriptase Inhibitors

Published on: May 9, 2025

High-throughput Screening for Broad-spectrum Chemical Inhibitors of RNA Viruses11:34

High-throughput Screening for Broad-spectrum Chemical Inhibitors of RNA Viruses

Published on: May 5, 2014

Related Concept Videos

Antiviral Nucleoside Inhibitors01:22

Antiviral Nucleoside Inhibitors

Antiviral Nucleoside InhibitorsAntiviral nucleoside inhibitors are structural analogs of natural nucleosides that interfere with viral DNA or RNA synthesis. These compounds selectively target viral polymerases due to their resemblance to host nucleosides, thereby disrupting viral genome replication.Mechanism of Acyclovir ActionAcyclovir is a guanosine analog with a three-carbon acyclic side chain. It selectively targets herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2),...
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,...
Retroviruses02:33

Retroviruses

Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
Viral Hepatitis I: Introduction01:28

Viral Hepatitis I: Introduction

Viral hepatitis is an inflammatory condition of the liver caused by infection with hepatotropic viruses, most commonly hepatitis A, B, C, D, and E. Despite variations in structure and transmission, all viruses mentioned infect hepatocytes and provoke immune responses that can hinder liver function. Additionally, some non-hepatotropic viruses can also lead to hepatic inflammation.Hepatitis A VirusHepatitis A virus (HAV) is transmitted through the fecal–oral route, typically by ingestion of food...
Drug Metabolism: Phase II Reactions01:14

Drug Metabolism: Phase II Reactions

Phase II reactions are essential for the detoxification and elimination of drugs from the body. These reactions involve the conjugation of parent drugs or their phase I metabolites with endogenous molecules, resulting in more hydrophilic drug conjugates. The primary conjugation reactions in this phase are sulfation and glucuronidation. Both sulfation and glucuronidation typically produce biologically inactive metabolites. However, in some cases involving prodrugs, active metabolites may be...
Bioactivation and Tissue Toxicity01:25

Bioactivation and Tissue Toxicity

Bioactivation is a metabolic process that transforms less reactive substances into highly reactive metabolites, initiating tissue toxicity. This transformation can lead to various toxic effects, including carcinogenesis and teratogenesis. Reactive metabolites are classified into two main types: electrophiles and free radicals.Electrophiles are electron-deficient species and are produced primarily by the enzyme cytochrome P-450 during the metabolism of compounds containing carbon, nitrogen, or...