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Acetaminophen (Ofirmev, Paracetamol)

Anesthesia Implications

Updated On: July 3, 2026

Classification:
Analgesic, Antipyretic
Therapeutic Effects:
Analgesia, Antipyretic
Primary Considerations:

Neonates and infants - these patients form a reactive intermediate metabolite that causes hepatocellular damage, especially after repeated doses. These patients are more susceptible to toxicity if they are acutely malnourished and/or dehydrated. Also, Neonates possess very little glucuronyl tranferase. Therefore, in these patients, acetaminophen administration is especially risky of toxic effects and administration should err on the side of safety. No conversions necessary - The maximum daily dose of acetaminophen is based on all routes of administration (i.e. intravenous, oral, and rectal) and all products containing acetaminophen. Maximum doses in 24 hours: 2-12 years old: 75 mg/kg per day 13+ years old and LESS than 50 kg: 75 mg/kg per day 13+ years old and MORE than 50 kg: 4000 mg per day IV side effects (most common): Adult: nausea, vomiting, headache, and insomnia Pediatric: nausea, vomiting, constipation, pruritus, agitation, and atelectasis

Contraindications:

Absolute: Severe hepatic impairment or severe active liver disease

Relative: hepatic impairment or active hepatic disease, in cases of alcoholism, chronic malnutrition, severe hypovolemia, or severe renal impairment (creatinine clearance ≤ 30 mL/min)

IV push dose:

2-12 years of age: 15 mg/kg every 6 hours or 12.5 mg/kg every 4 hours, with a maximum single dose of 15 mg/kg, a minimum dosing interval of 4 hours, and a maximum daily dose of acetaminophen of 75 mg/kg per day. 13 years of age and above: less than 50 kg: the recommended dosage is 15 mg/kg every 6 hours or 12.5 mg/kg every 4 hours, with a maximum single dose of 15 mg/kg, a minimum dosing interval of 4 hours, and a maximum daily dose of acetaminophen of 75 mg/kg per day. greater than 50 kg: 1000 mg every 6 hours, or 650 mg every 4 hours, with a maximum single dose of 1000 mg, a minimum dosing interval of 4 hours, and a maximum daily dose of acetaminophen of 4000 mg per day

Metabolism:

Metabolized by glucuronyl tranferase (the same enzyme that facilitates conjugation of bilirubin)

Additional Notes:

Rectal dosing: 10 - 15 mg/kg

Reference

Nagelhout. Nurse anesthesia. 5th edition. 2014.
Ofirmev label. 2010.
Gandi. Postoperative analgesic efficacy of single high dose and low dose rectal acetaminophen in pediatric ophthalmic surgery. 2012.
Health Technology Inquiry Service. Dosing recommendations for acetaminophen in pediatrics: Guidelines and a clinical review. 2008.
Acetaminophen Injection. FDA PI (Fresenius Kabi). 2022.link
Acetaminophen Injection. DailyMed (current FDA label).link