Hyperammonemia, Neonatal — Amino Acid and Nitrogen-scavenger Therapy — Clinical Pathway: Emergency Department and ICU

Neonatal Hyperammonemia Clinical Pathway — PICU and Emergency Department

Amino Acid and Nitrogen-scavenger Therapy

  • During metabolism waste nitrogen becomes ammonia (causes negative side effects) or urea which is safely excreted in urine.
  • Arginine is an essential amino acid that drives the urea cycle by converting nitrogen into urea, which helps lower ammonia.
  • Sodium phenylacetate and sodium benzoate (Ammonul®) binds with amino acids (glutamine and glycine) to make them water-soluble, allowing the body to excrete nitrogen in urine and also lowers ammonia.
  • Start these medications as soon as possible to lower child’s ammonia to reduce risk of permanent brain damage.
  • Central line is preferred as both medications have vesicant-like properties.
    • They may be administered peripherally if this is the only access available.
    • Peripheral infusion may result in local irritation or burning. Monitor site carefully.

Arginine and Sodium Phenylacetate + Sodium Benzoate (Ammonul)

Medication Dosing Special Considerations
Arginine
  • IV Loading dose
    • 0.6 g/kg*
    • Administer over 90 minutes
  • IV Maintenance infusion
    • 0.6 g/kg*
    • Administered over 24 hours
  • *Dose adjustment
    • If deficiencies of argininosuccinate synthetase (ASS) or argininosuccinate lyase (ASL) are excluded as diagnostic possibilities, reduce the I.V. dose of arginine to 0.2 g/kg/day
  • Hyperchloremic acidosis may occur after high-dose arginine hydrochloride administration
  • Monitor plasma levels of chloride, bicarbonate (and potassium)
  • Treat with appropriate amounts of bicarbonate as needed
Sodium Phenylacetate + Sodium Benzoate (Ammonul)
  • IV Loading Dose
    • Sodium phenylacetate 250 mg/kg + sodium benzoate 250 mg/kg
    • Administer over 90-120 minutes
  • IV Maintenance infusion
    • Sodium phenylacetate 250 mg/kg + sodium benzoate 250 mg/kg
    • Administered over 24 hours
  • Metabolism service approval required
  • Do not repeat loading dose
  • Note:
    • Loading dose and the maintenance infusion will be the same volume
  • Flush with D5W or D10W
  • Continue therapy until ammonia levels are in normal range
  • Check compatibility with other vital medications   or with a pharmacist