What is the toxic dose of acetaminophen (N-acetyl-p-aminophenol) for a 16-year-old?

From the Guidelines

The toxic dose of acetaminophen for a 16-year-old is generally considered to be more than 150 mg/kg as a single ingestion, which is the same threshold used for adults. For most 16-year-olds, this would equate to approximately 7,500-12,000 mg (7.5-12 grams) depending on their weight. Acute ingestion exceeding 250 mg/kg or 12 grams total (whichever is less) is considered potentially lethal.

Key Considerations

• For therapeutic use, the maximum recommended daily dose should not exceed 4,000 mg (4 grams) in 24 hours, with individual doses typically being 650-1000 mg every 6 hours.
• Acetaminophen toxicity primarily affects the liver through the production of a toxic metabolite called N-acetyl-p-benzoquinone imine (NAPQI), which depletes glutathione stores and causes hepatocellular damage.
• Risk factors that may lower the toxic threshold include malnutrition, chronic alcohol use, and certain medications that induce liver enzymes.
• If acetaminophen overdose is suspected, immediate medical attention is crucial, as the antidote N-acetylcysteine is most effective when administered within 8 hours of ingestion, as supported by studies such as those reported by Smilkstein et al 1 and Prescott et al, as referenced in 1.

Important Evidence

• The management of acetaminophen overdose, including the use of the Rumack-Matthew nomogram for risk stratification, is discussed in detail in studies such as 1 and 1.
• The effectiveness of N-acetylcysteine in preventing hepatotoxicity when administered promptly after acetaminophen overdose is highlighted in various studies, including those referenced in 1.

From the FDA Drug Label

The acute ingestion of acetaminophen in quantities of 150 mg/kg or greater may result in hepatic toxicity. For a 16-year-old, to determine the toxic dose of acetaminophen, we need to consider their weight. However, since the weight of the individual is not provided, we can only give a general guideline based on the information given in the drug label.

• The toxic dose is 150 mg/kg or greater.
• To calculate this for a 16-year-old, we would need their weight in kilograms.
• Assuming an average weight for a 16-year-old (which can vary widely), the toxic dose would be 150 mg/kg times their weight in kilograms. Given the information from 2, without the specific weight of the individual, we cannot calculate an exact toxic dose for this person.

From the Research

Toxic Dose of Acetaminophen for a 16-Year-Old

The toxic dose of acetaminophen for a 16-year-old can be determined based on the guidelines provided in the studies.

• According to the study 3, patients 6 years of age or older should be referred to an emergency department if they have ingested at least 10 g or 200 mg/kg (whichever is lower) of acetaminophen.
• The study 4 suggests that adolescents who ingest acetaminophen in a suicidal or manipulative attempt should be evaluated with a plasma acetaminophen level 4 or more hours after ingestion, and treated with the antidote NAC if the level is in the potentially toxic range.
• The study 5 states that for an acute overdose, most adults must ingest about 12g or more acetaminophen before the risk of serious hepatotoxicity is of concern, but this may not directly apply to a 16-year-old.

Determining the Toxic Dose

Based on the information provided in the studies:

• A 16-year-old would be considered in the category of patients 6 years of age or older, as per the study 3.
• The toxic dose for this age group is at least 10 g or 200 mg/kg (whichever is lower) of acetaminophen.
• To determine the toxic dose for a specific 16-year-old, their weight in kilograms would need to be considered, as the toxic dose is also dependent on the weight of the individual.

Important Considerations

• It is crucial to note that these guidelines are based on the available studies and may not cover all specific scenarios or individual circumstances.
• The studies 3, 4, and 5 provide valuable information on the management and treatment of acetaminophen overdose, but the determination of the toxic dose should be made by a healthcare professional, taking into account the individual's specific situation and medical history.