Ethanol serves as a competitive inhibitor of which substance's metabolism?

Ethanol acts as a competitive inhibitor in the metabolism of ethylene glycol. Ethylene glycol is metabolized by the enzyme alcohol dehydrogenase, which is the same enzyme that metabolizes ethanol. When both ethanol and ethylene glycol are present, ethanol competes for binding to this enzyme, effectively reducing the rate at which ethylene glycol is metabolized into toxic metabolites.

By inhibiting the metabolism of ethylene glycol, ethanol helps to prevent the formation of harmful by-products that can lead to severe toxicity, such as metabolic acidosis and renal failure. This therapeutic intervention is a critical treatment in cases of ethylene glycol poisoning, as it allows the body time to eliminate ethylene glycol before it is converted into more harmful substances.

The other substances listed do not have the same pathway or interaction with ethanol in terms of metabolism. Acetaminophen, ibuprofen, and phenobarbital are metabolized through different pathways that do not involve the competitive inhibition by ethanol in the same manner. Understanding this mechanism is essential for managing cases of poisoning and implementing the appropriate treatment strategies.