What is the administration protocol for 1 gram of acetaminophen (paracetamol) intravenous (IV) injection?

From the Guidelines

To administer 1 gram of paracetamol injection, it should be given as an intravenous infusion over 15 minutes, with a loading dose of 15 to 20 mg kg-1, and subsequent doses of 10-15 mg kg-1 every 6-8 hours, as recommended by the most recent guidance 1. The administration of paracetamol injection requires careful consideration of the patient's weight, as the dosage is based on a milligram per kilogram basis.

• The standard loading dose is 15 to 20 mg kg-1, which can be calculated based on the patient's weight, with a maximum dose of 1 gram (100mL of a 10mg/mL solution) for adults.
• The subsequent doses should be 10-15 mg kg-1 every 6-8 hours, with a maximum daily dose not exceeding 4 grams in adults with normal liver function.
• It is essential to monitor the patient during administration for any adverse reactions, such as hypotension or allergic responses.
• Paracetamol injection is a useful alternative for patients who cannot take oral medications or require rapid pain relief or fever reduction, as it provides analgesic and antipyretic effects without the gastrointestinal side effects associated with NSAIDs, as seen in the guidance provided by the European Society for Paediatric Anaesthesiology 1.

From the FDA Drug Label

OFIRMEV should be administered only as a 15-minute intravenous infusion. Adults and Adolescents Weighing 50 kg and Over: 1000 mg every 6 hours or 650 mg every 4 hours to a maximum of 4000 mg per day. Each 100 mL glass vial or bag contains 1000 mg acetaminophen (10 mg/mL).

To administer 1gm paracetamol injection, it should be given as a 15-minute intravenous infusion. The recommended dose for adults and adolescents weighing 50 kg and over is 1000 mg every 6 hours. Each 100 mL of the injection contains 1000 mg of acetaminophen, which can be administered directly as it matches the required dose of 1gm. 2

From the Research

Administration of 1gm Paracetamol Injection

• The administration of 1gm paracetamol injection is typically done as an intravenous (i.v.) infusion, with a maximal daily dose of 4 g/day 3.
• The pharmacokinetic profile of paracetamol is assessed after both the initial dose and subsequent doses, with plasma concentrations ranging from 67.9+/-21.8 mug/ml (peak plasma concentration) to 6.2+/-2.3 mug/ml (trough plasma concentration) without any toxic range for any subject 3.
• Repeated 1-g infusions of paracetamol result in plasma concentrations approximately 35% lower than those measured after a 2-g dose, showing no accumulation 3.

Safety and Efficacy

• The safety and efficacy of 1gm paracetamol injection have been evaluated in several studies, with results showing that it is well tolerated and provides effective analgesia 4, 5.
• A study comparing the efficacy and safety of single and repeated administration of 1 gram intravenous acetaminophen injection (paracetamol) for pain management after major orthopedic surgery found that it provided rapid and effective analgesia and was well tolerated 4.
• Another study found that intravenous paracetamol 1 g generally provided significantly better analgesic efficacy than placebo treatment in adult patients who had undergone dental, orthopaedic or gynaecological surgery 5.

Special Considerations

• The use of paracetamol in patients with liver impairment is a controversial subject, with some studies suggesting that it may be safe to use in certain cases, while others recommend caution 6, 7.
• A study reviewing the factors that increase the risk of hepatocellular injury from paracetamol and the pharmacokinetic alterations in different pathologies of chronic liver disease found that inadvertent under-dosing may result in concentrations too low to enable efficacy 6.
• Another study found that liver injury induced by paracetamol is a common cause of acute liver injury, and that hepatotoxicity from paracetamol overdose, whether intentional or non-intentional, is the most common cause of DILI in the United States 7.