MORPHINE HYDROCHLORIDE

Morphine

Reviewed by Dr Carl Kuschel, Simon Rowley, and Brenda Hughes
February 2001
Administration Newborn Drug Protocol Index Newborn Services Home Page

 

Dose and Administration

Neonatal Abstinence Syndrome

  1. Start at 500 micrograms/kg/day orally 1
    This is usually prescribed 6-hourly. Dose may need to be increased with severe withdrawal before weaning can take place.
  2. Reduce dose by 10-15% of the original dose every 2-3 days as tolerated.

Analgesia

  1. Ventilated 100 - 200 micrograms/kg/dose.
  2. Non-ventilated 50 micrograms/kg/dose

Indications

  1. Neonatal Abstinence Syndrome
  2. Sedation

Contraindications and Precautions

  1. Known hypersensitivity to opiates.
  2. Hypovolaemia, hypotension.
  3. Caution in preterm infants, especially very immature.
  4. Caution in neonates with hepatic and renal impairment.
  5. Caution in neonates with cardiac arrhythmias.

Clinical Pharmacology

Morphine hydrochloride is a narcotic analgesic which stimulates opioid receptors in the central nervous system (mimics actions of encephalins and β endorphins). Produces respiratory depression by direct effect upon brain stem respiratory centres. No major effect upon cardiovascular system in analgesic doses. Resistance and capacitance vessels are dilated by the opioids. Gastrointestinal secretions and motility are decreased while tone is increased. Stimulates smooth muscle of biliary and urinary tracts.

Well absorbed from gastrointestinal tract but high first pass hepatic metabolism. Low binding (20%) to human plasma protein. Hepatic metabolism to glucuronide and other metabolites. Excretion via the kidney - significant amounts of unchanged drug in the neonate. The pharmacokinetics of morphine in the neonate are very variable.

Variable onset of action after oral administration. Analgesic effects occur with plasma concentrations around 120ng/ml. Respiratory depression occurs with plasma concentrations >300ng/ml. In the non-withdrawing baby respiratory depression is more likely.

Possible Adverse Effects

  1. Respiratory depression.
  2. Gastrointestinal disturbances (vomiting and spilling, ileus, delayed gastric emptying, cramps, and constipation.
  3. Hypotension
  4. Physical dependence
  5. Urinary retention.

Special Considerations

  1. Morphine is the drug of choice for most situations requiring pain relief
  2. Wean slowly after prolonged use of morphine.
  3. Management of morphine toxicity: stop morphine, support infant (ventilation, external cardiac massage, volume expansion etc.), Naloxone (0.1 - 0.2 mg/kg/dose IM). Naloxone is never used for babies with Neonatal Abstinence Syndrome.
  4. For further information about its use in narcotic withdrawal see Neonatal Abstinence Guideline.