N-acetyl-p-benzoquinone imine (NAPQI) (NAPQI)

N-acetyl-p-benzoquinone imine (NAPQI) is the principal reactive metabolite formed during acetaminophen metabolism. Generated by cytochrome P450 oxidation, NAPQI is highly electrophilic and binds covalently to cellular thiols, especially glutathione. At therapeutic doses, NAPQI is rapidly detoxified by conjugation with glutathione, but in overdoses or compromised detoxification, buildup of NAPQI causes extensive hepatic and cellular protein damage, leading to hepatotoxicity. NAPQI and related reactive metabolites also interact with hepatic enzymes such as thioredoxin reductase, further contributing to oxidative stress and liver injury. The metabolites can sensitize and activate TRPV1 channels, potentially influencing analgesic and cytotoxic effects. Drug interventions focus on preventing or reversing NAPQI toxicity by replenishing glutathione reserves or modulating its formation.

Other names

Reactive acetaminophen metabolitesNAPQIp-benzoquinone imineAPAP reactive metaboliteacetaminophen electrophilic intermediate

Toxic metabolites covalently bind to and damage hepatic proteins and enzymes (e.g., glutathione, thioredoxin reductase)\nCause cell death by depleting cellular antioxidants\nSensitize and activate TRPV1 channels