Free radicals and antioxidants, xenobiotic metabolism
Biochemistry · MBBS
Study notes
Paracetamol overdose destroys the liver — but only past a threshold. Normally paracetamol is safely conjugated (Phase II); overdose saturates that, shunting it through CYP450 (Phase I) into NAPQI — a toxic free-radical-like metabolite that depletes glutathione and kills hepatocytes. N-acetylcysteine (NAC) restores glutathione — the antidote — but only within ~8 hours. The overdose story is xenobiotic metabolism's dark side: the same enzymes that detoxify can toxify.
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