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Drug dosage identifier

Paracetamol (Intravenous)

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Dose and Administration

Postmenstrual Age  (weeks)  Dose  (mg/kg/dose) Interval  (hours) Maximum Dose
<32/40 7.5 8 22.5 mg/kg/day
≥ 32/40 7.5 6 30 mg/kg/day



Intravenous Paracetamol use should be reviewed daily on ward rounds.

It is recommended to use a suitable oral or rectal analgesic treatment as soon as practicable.


  • known sensitivity to paracetamol
  • Severe hepatocellular insufficiency
  • When oral or rectal route available


  • Use in the 1st 24 hours after birth (see Special Considerations).
  • Moderate or severe pain where a more potent analgesic may be more appropriate
  • Use in extremely preterm infants
  • Impaired hepatic or kidney function
  • Unconjugated hyperbilirubinaemia (clearance is reduced)
  • G6PD deficiency (may lead to haemolytic anaemia)
  • Hypovolaemia

Clinical pharmacology

Paracetamol has analgesic and antipyretic actions but only weak anti-inflammatory properties. It inhibits prostaglandin biosynthesis in conditions associated with low levels of cellular peroxides (pain, fever).

Due to metabolic immaturity, neonatal clearance of paracetamol is different from adults. Sulphate conjugation is well developed in a neonate and is the major metabolic pathway for paracetamol clearance. Glucuronidation clearance is not well developed and plays a minor role in paracetamol clearance in neonates. With maturation these clearance pathways for paracetamol change. The usual adult ratio of 2:1 glucuronide to sulphate conjugates of paracetamol is achieved by 12 years of age.

The enzyme systems P450 CYP2E1, 1A2, 3A4 are responsible for forming paracetamol toxic metabolites. Despite a low activity of P450 CYP 2E1 in neonates, toxic metabolites can still be formed.

In neonates, the half life of intravenous paracetamol is approximately 3.5 hours.

Possible adverse effects

  • Pain at injection site
  • Hypotonia
  • Nausea and vomiting
  • Fever

Special considerations

  • Clinical experience in neonates, especially those preterm, is limited.
  • Caution in the 1st 24 hours for treatment of "pain" related to birth. Infants who are unsettled should be assessed clinically and not assumed to be in pain secondary to birth.

Management of IV Paracetamol administration


  • Perfalgan ® (paracetamol) 500mg/50ml, solution for infusion
  • Perfalgan ® (paracetamol) 1000mg/100ml, solution for infusion
  • Solution is clear to slightly yellowish


  • Stat dose to be charted on stat page of prescription chart in mg/dose.
  • Maintenance doses are charted on the prescription chart in mg/dose.
  • Review prescription every 24 hours or earlier as indicated.


Slow IV Infusion

  • Dilution is generally not required unless the baby weighs <1000 grams.
  • Dilute to 2 mg/ml for use in ELBW infants using sodium chloride 0.9% or glucose 5%. If diluted, the solution should be used immediately (do not store for more than one hour, including the infusion time).
  • Filter through a Pall (0.2 micron) filter prior to administration.
  • Administer by slow IV bolus over 15 minutes.
  • Flush the line before and after administration with sodium chloride 0.9%.
  • Compatible with glucose 5% and sodium chloride 0.9%.
  • Incompatible with Intralipid solution
  • Do NOT mix with other drugs, blood or blood products.

Observation and documentation

Observe for signs of adverse effects.


  • Store unopened in the outer packaging at room temperature below 30°C.
  • Do not refrigerate or freeze.
  • Use immediately after opening and discard the remaining solution.


  1. Anderson BJ, Allegaert K. Intravenous neonatal paracetamol dosing:the majic of 10 days.Pediatric Anesth 2009;19:289-295.
  2. Anderson BJ, Wollard GA, Holford NH. A model for size and age changes in the pharmacokinetics of paracetamol in neonates, infants and children. Br J Clin Pharmacol 2000; 50(2):125-134.
  3. Wilson-Smith EM, Morton NS. Survey of i.v. paracetamol (acetaminophen) use in neonates and infants under 1 year of age by UK anesthetists. Pediatric Anesth 2009; 19(4):329-337.
  4. Perfalgan®.Data Sheet. Auckland:Bristol-Myers Squibb (NZ) Limited., October 2010. Available from URL:

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Document Control

  • Date last published: 28 February 2011
  • Document type: Drug Dosage Guideline
  • Services responsible: ADHB Pharmacy, Neonatology, Paediatric Pain Service
  • Editor: Sarah Bellhouse
  • Review frequency: 2 years