Reviewed by Dr Carl Kuschel and Brenda Hughes
October 2004
Administration Newborn Drug Protocol Index Newborn Services Home Page


Dose and Administration

  1. Sedation and analgesia: 1-4 micrograms/kg/dose IV slow push, IM.
    1. For intubation, use 4micrograms/kg
    2. Repeat as required (usually every 2-4 hours).
    3. May be given as a continuous infusion: 1-5 micrograms/kg/hour.
  2. Anaesthesia: 5-50 micrograms/kg/dose.
    1. Minor surgery 5-20 micrograms/kg/dose.
    2. Major surgery 30-50 micrograms/kg/dose.
Fentanyl (micrograms) in 50ml IV solution =  50 x weight (kg) x dose (micrograms/kg/hour)
                   IV rate (ml/hour)

Usual strength = 2-10 micrograms/ml.


  1. Intubation
  2. Analgesia
  3. Sedation
  4. Anaesthesia

Contraindications and Precautions

  1. Known hypersensitivity to fentanyl and/or other opiates.
  2. Bradyarrhythmias.
  3. Myasthenia gravis
  4. Caution in preterm infants, especially extreme immaturity.
  5. Caution in neonates with hepatic or renal impairment
  6. Caution in nonventilated neonates with respiratory distress.
  7. Caution in neonates with raised intracranial pressure.

Clinical Pharmacology

Fentanyl citrate, a narcotic analgesic, is 50-100 times more potent than morphine. Actions qualitatively similar to those of morphine. Produces a minimum of cortical depression. Alterations in respiratory rate and alveolar ventilation may last longer than analgesic effect. No significant cardiovascular effects at usual therapeutic doses.

Rapid distribution with sequestration in fat. Wide variability in distribution volume (Vd 1-13 L/kg). Extensive binding to human plasma protein. Hepatic metabolism. Excretion via the kidney. Elimination half-life very variable in neonates (6-32 hours). Onset of action almost immediate with IV administration (7-8 minutes with IM). Peak effect 5-15 minutes following IV injection. Duration of the analgesic effect 30-60 minutes (1-2 hours with IM).

Possible Adverse Effects

  1. Bradycardia (rapid administration).
  2. Respiratory depression.
  3. Decrease in physical activity.
  4. Physical dependence.
  5. Rapid tolerance with prolonged use (>2 days).
  6. Nausea and vomiting.
  7. Severe muscle rigidity, especially chest wall rigidity.  Can be avoided with slow IV pushes rather than rapid boluses.  Have suxamethonium ready.

Special Considerations

  1. Faster onset of action but shorter duration of action than morphine.
  2. Additive effects with other narcotics and/or other central nervous system depressants.
  3. With prolonged use the minimum effective dose may increase as tolerance develops.
  4. After continuous use, discontinue fentanyl over a few days because physical dependence develops.
  5. Management of fentanyl overdose and/or toxicity: discontinue fentanyl, supportive therapy (ventilation, etc.), naloxone (0.01-0.1 mg/kg/dose IV).