What is the risk of acetaminophen toxicity in an individual weighing 105 kilograms who ingested 1500 milligrams of Tylenol (acetaminophen) at once?

From the Guidelines

An individual weighing 105 kg who ingested 1500mg of acetaminophen (Tylenol) at once is at low risk of acute liver injury since the ingested dose is below the recommended threshold.

Risk Assessment

• The maximum recommended daily dose of acetaminophen is 4000mg, and taking 1500mg at once is approximately 37.5% of this daily limit 1.
• The risk of liver injury increases with single doses above 7000mg or 150mg/kg in adults, but in this case, the ingested dose of 1500mg is approximately 14.3mg/kg, which is below the 150mg/kg threshold 1.
• According to the Rumack-Matthew nomogram, patients with a single acute poisoning at a known time who are no more than 24 hours postingestion can be risk-stratified for hepatotoxicity 1.

Management

• Although the risk is low, medical attention is still warranted to monitor for potential liver damage, as some studies suggest that repeated supratherapeutic ingestions of acetaminophen may result in hepatotoxicity, hepatic failure, and even death 1.
• The FDA recommends that patients be advised to limit daily acetaminophen intake to a maximum of 4 g, and imposes a limit of 325 mg of acetaminophen per tablet, capsule, or other dosage unit in prescription products to reduce the risk of severe liver injury from acetaminophen overdosing 1.
• N-acetylcysteine (NAC) is recommended for patients with suspected or known acetaminophen overdose, including repeated supratherapeutic ingestions, to reduce the risk of hepatotoxicity and hepatic failure 1.

From the FDA Drug Label

WARNINGS Liver warning: This product contains acetaminophen. Severe Liver damage may occur if you take • more than 6 caplets in 24 hours, which is the maximum daily amount The risk of acetaminophen toxicity in an individual weighing 105 kilograms who ingested 1500 milligrams of Tylenol (acetaminophen) at once cannot be determined from the information provided in the drug label, as it does not provide a clear dosage limit based on weight or a specific toxic dose. 2

From the Research

Acetaminophen Toxicity Risk

The risk of acetaminophen toxicity in an individual weighing 105 kilograms who ingested 1500 milligrams of Tylenol (acetaminophen) at once can be assessed based on the available evidence.

• The ingested dose of 1500 milligrams is below the maximum daily therapeutic dose of 3900-4000 mg established by the FDA 3.
• However, the risk of hepatotoxicity is not solely determined by the dose ingested, but also by individual factors such as weight and the presence of other risk factors 4, 5.
• A study evaluating the sensitivity and specificity of dose-estimates for acute acetaminophen overdose found that the 150 mg/kg dose-estimate had a sensitivity of 92.6% and a specificity of 55.3% for predicting hepatotoxicity risk 6.
• In this case, the ingested dose of 1500 milligrams corresponds to approximately 14.3 mg/kg (1500 mg / 105 kg), which is below the 150 mg/kg threshold considered to be at risk for hepatotoxicity 6.
• Therefore, based on the available evidence, the risk of acetaminophen toxicity in this individual appears to be low, but it is essential to monitor for signs of hepatotoxicity and consider individual factors that may increase the risk of toxicity 4, 5.