GAP-109
You gave how much Tylenol?!?
McKenzie S, Soneru C, Lester A, Falcon R, Petersen T
University of New Mexico, Albuquerque, NM, USA
We present a case of intravenous acetaminophen (Ofirmev®) overdose in a healthy 2-year-old male weighing 11.6 kg. The patient presented to the emergency department with a type II left supracondylar humerus fracture. He was taken to the operating room for closed reduction and percutaneous pinning.
After an uneventful general anesthetic, he was transferred to the post anesthesia care unit for recovery, where he was scheduled to receive a dose of 174 mg (15 mg/kg) of Ofirmev® delivered via syringe pump. Due to a pump error, the patient instead received 1,000 mg (86.2 mg/kg) of Ofirmev®. The Poison Control Center was contacted. They informed the provider that because the patient received less than 150 mg/kg/24 hours, he would not need to be treated with N-acetylcysteine, the antidote for acetaminophen overdose. Also, the provider was advised to not give any additional doses of Ofirmev® over the next 24 hours.
About four hours later, the patient’s serum acetaminophen level was 28 mcg/ml, which was actually within the therapeutic range of 10-30 mcg/ml. Acetaminophen is considered toxic if the level is greater than 150 mcg/ml. The patient was admitted overnight for observation. He did not develop any signs or symptoms of acetaminophen toxicity (e.g. abdominal upset or pain, nausea, vomiting, decrease oral intake, jaundice, diarrhea, convulsions). Liver function tests and coagulation tests drawn the following morning were within normal limits. The patient was discharged home without limitations.
Ofirmev® is an effective and commonly administered postoperative analgesic agent. The manufacturer recommends to not exceed a maximum total daily dose of 75 mg/kg for children between the ages of 2 to 12 years old1. Doses in excess of 150 mg/kg/24 hours can exceed the hepatic capacity of glutathione conjugation, resulting in the accumulation of N-acetyl-p-benzoquinone imine (NAPQI) which can cause severe hepatic injury and in some cases, death2. NAPQI is the toxic byproduct of CYP2E1 metabolism of acetaminophen. By one year of age, CYP2E1 expression and activity is similar to that of an adult3.
Although our patient tolerated an Ofirmev® dose that exceeded the manufacturer’s recommendation, great caution should be taken with the administration of this medication in the pediatric population. Younger children can have an undiagnosed myopathy. Acetaminophen toxicity and liver failure have been reported in patients with myopathies who have received acetaminophen doses within the therapeutic range 4, 5.
REFERENCES
1. HIGHLIGHTS OF PRESCRIBING INFORMATION for OFIRMEV (acetaminophen) injection, Cadence Pharmaceuticals, Inc. San Diego, CA 92130. Revised: 11/2010
2. Ogilvie JD, Rieder MJ, Lim R. Acetaminophen overdose in children. CMAJ. 2012 Sep 18; 184(13): 1492-1496
3. Hines RN. The ontogeny of drug metabolizing enzymes and implications for adverse drug events. Pharmacol Ther 2008;118: 250–67
4. Ceelie I, James LP, Gijsen V, et al. Acute liver failure after recommended doses of acetaminophen in patients with myopathies. Crit Care Med. 2011 Jan 14;
5. Pearce B, Grant IS. Acute liver failure following therapeutic paracetamol administration in patients with muscular dystrophies. Anaesthesia. 2008 Jan;63(1):89–91
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