# A 22-year-old client is brought to the ED 6 hours after intentionally ingesting 30 tablets of acetaminophen 500 mg. Vital signs stable, asymptomatic; serum acetaminophen level is in the toxic range on the Rumack-Matthew nomogram. Which medication does the nurse anticipate administering?

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> subject: Adverse Effects/Contraindications/Interactions  
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## Question

A 22-year-old client is brought to the ED 6 hours after intentionally ingesting 30 tablets of acetaminophen 500 mg. Vital signs stable, asymptomatic; serum acetaminophen level is in the toxic range on the Rumack-Matthew nomogram. Which medication does the nurse anticipate administering?

## Option

1. IV or oral N-acetylcysteine (Mucomyst, Acetadote) loading dose followed by maintenance dosing for at least 21 hours, ideally within 8 hours of ingestion. **✔ Correct answer**
2. Administration of a single dose of activated charcoal now, as it remains a recommended intervention to bind acetaminophen for up to 12 hours after ingestion.
3. Intravenous sodium bicarbonate to alkalinize the urine and enhance renal excretion of the hepatotoxic NAPQI metabolite following massive acetaminophen ingestion.
4. Intravenous naloxone administered via IV push to reverse the opioid-like sedation that can occur after intentional acetaminophen overdose.

**Correct answer: 1**

## Explanation

N-acetylcysteine (NAC, Mucomyst, Acetadote) is the antidote for acetaminophen toxicity. NAC restores hepatic glutathione and detoxifies NAPQI, the toxic metabolite. The Rumack-Matthew nomogram (using a 4-hour or later post-ingestion level) determines treatment thresholds. Maximum protection is achieved when NAC is started within 8 hours of ingestion; treatment is still beneficial up to 24 hours and beyond if hepatotoxicity has developed. Routes: IV (Acetadote) is preferred when the patient cannot tolerate oral, has GI bleeding, fulminant hepatic failure, or pregnancy; standard IV regimen is a 150 mg/kg loading dose over 60 minutes, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours, with longer infusions if liver injury is established. Oral regimen is 140 mg/kg loading then 70 mg/kg every 4 hours for 17 doses; the strong sulfur (rotten egg) odor causes nausea — give with juice or carbonated drink, antiemetic, or NG tube. Sodium bicarbonate, charcoal alone after 4 hours, and naloxone do not address the hepatotoxic mechanism. Activated charcoal can adjunct within 1 to 2 hours of ingestion, not 6.

## In-depth explanation

N-acetylcysteine ASAP, ideally within 8 hours, IV preferred for severe cases. The Rumack-Matthew nomogram drives the decision; do not wait for symptoms because hepatotoxicity is silent until day 2 to 4.

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