Postmarketing review of intravenous acetaminophen dosing based on Food and Drug Administration prescribing guidelines

Abstract

Study objectives: To evaluate the appropriateness of intravenous acetaminophen dosing-prescribed dose, frequency, duration, and indication-based on United States Food and Drug Administration (FDA)-approved prescribing guidelines and to evaluate the adverse effect profile of intravenous acetaminophen.

Design: Retrospective chart review.

Setting: United States Navy medical center.

Patients: Three hundred patients who received intravenous acetaminophen from August 1, 2011, to August 1, 2012.

Measurements and main results: The indications, dose, frequency, and duration of intravenous acetaminophen were recorded for each patient. Adverse effects of intravenous acetaminophen were analyzed by thoroughly reviewing any adverse effects documented, including nausea, vomiting, headache, or any symptom specifically attributed to the drug. Baseline liver function tests, including aspartate aminotransferase and alanine aminotransferase levels, and elevations 3 times the upper limit of normal during intravenous acetaminophen therapy were recorded. The average patient weight was 78±21 kg, with 12 patients (4%) weighing less than 50 kg and 288 (96%) patients weighing 50 kg or greater. Two hundred forty-one patients (80%) were appropriately dosed, whereas 59 (20%) patients were not appropriately dosed based on the FDA-approved dosing. No patients exceeded the FDA-approved maximum daily dosing recommendations for intravenous acetaminophen (4 g). Sixty-five patients (22%) received intravenous acetaminophen for longer than 24 hours. Intravenous acetaminophen was well tolerated, without any reported adverse effects, including the commonly reported adverse effects of nausea, vomiting, headache, and insomnia. Ten patients (3%) had a documented history of liver disease and did not experience any adverse effects or increases in liver function tests after the administration of intravenous acetaminophen.

Conclusion: Intravenous acetaminophen appeared to be a safe and effective analgesic and antipyretic agent. Dosing for patients weighing less than 50 kg needs to be appropriately weight adjusted. Intravenous acetaminophen can be used alone or in conjunction with opioids and other analgesics. Limitations of this study include its retrospective design, inability to assess outcomes of reducing opioid use, and short-term observation period.

Keywords: IV acetaminophen; Ofirmev; paracetamol.