What medication is typically administered to counteract toxic acetaminophen levels?

Acetylcysteine is the specific antidote used to counteract toxic levels of acetaminophen. It works by replenishing glutathione, a critical antioxidant that helps neutralize the toxic metabolites of acetaminophen. When acetaminophen is ingested in excessive amounts, it depletes glutathione reserves in the liver, leading to potential hepatic toxicity. Acetylcysteine assists in preventing liver damage by facilitating the conversion of toxic metabolites back to non-toxic forms and promoting their elimination.

The timing of administration is crucial; acetylcysteine is most effective when given within 8 to 10 hours after an acetaminophen overdose, but it can still provide benefits even when administered later. This makes it an essential intervention in cases of suspected acetaminophen toxicity.

The other medications listed have specific uses but do not serve as antidotes for acetaminophen toxicity: Deferoxamine mesylate is used to treat iron overload, succimer is a chelating agent for heavy metal poisoning, and flumazenil is a benzodiazepine antagonist used for reversing the effects of benzodiazepines. Therefore, acetylcysteine stands out as the critical treatment for acetaminophen overdose.