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Antidote

Pediatric

ACETYLCYSTEINE

Parvolex, Mucomyst, N-Acetylcysteine, NAC

INDICATIONS

  • Treatment of acute acetaminophen overdose (refer to Matthew-Rumack nomogram at end of monograph)
  • Treatment of repeated supratherapeutic (chronic) acetaminophen ingestion
  • Treatment of fulminant hepatic failure due to acetaminophen overdose or other hepatotoxic toxins.

DOSAGE

a) Intravenous 21-hour protocol

N-Acetylcysteine
(NAC) 200mg/ml

Dilution
In D5W (most common) or .45% NaCl

Duration of Infusion

First Infusion
150mg/kg of NAC
150mg = 0.75ml

Place total dose of NAC in 3 ml/kg volume of IV fluid up to max of 200ml

1 hour

Second Infusion
50mg/kg
50mg = 0.25mls

Place total dose of NAC in volume of
10 ml/kg up to max of 500ml

4 hours

Third Infusion
100mg/kg
100mg = 0.5ml

Place total dose of NAC in 20 ml/kg volume of IV fluid up to max of
1000 ml

16 hours

b) Oral 20 hour protocol

  • Rarely, oral dosing is necessary for patients who develop refractory anaphylactoid reactions to intravenous NAC.
  • Loading dose: 140 mg/kg
  • Maintenance doses: 70 mg/kg every 4 hours for five doses

Example calculation of dilution for oral dosing for a 35 kg person:

Loading dose:

NAC 20%: 0.7 ml/kg (140 mg/kg) x 35 kg = 25 ml

Soda/Juice: 2 ml/kg x 35 kg = 70 ml

Total volume to administer: 25 ml + 70 ml = 95 ml

IMPORTANT NOTE: At completion of either the oral or intravenous protocol, if there is a positive acetaminophen level, an INR greater than 1.5, or AST or ALT > 50 IU/L, continuation of the maintenance doses is required. Duration will depend on multiple clinical and laboratory parameters and should be discussed with the IWK Regional Poison Centre 1-800-565-8161.

ADMINISTRATION

  • Oral: See “Dosage” section for dilution parameters
  • Infusion: Further dilute dose in D5W or normal saline and administer according to protocol.
  • Infusion: Infusion device is required.

COMPATIBILITY, STABILITY

Stable for 24 hours diluted in D5W or normal saline at room temperature.

POTENTIAL HAZARDS OF ADMINISTRATION

  • Nausea, vomiting.
  • Monitor heart rate and blood pressure before, during and after infusion.
  • Anaphylactoid reactions. Patients should be monitored closely during the first hour of drug administration. Symptoms include: pruritus, rash, facial edema, urticaria, flushing, chest tightness, tachycardia, hypotension and bronchospasm.
  • Anaphylactoid reactions may be related to the rate of administration and often occur during the loading dose. If anaphylactoid symptoms appear, temporarily discontinue the infusion and assess the patient. Administer diphenhydramine if required. If the reaction is severe follow usual practice for treatment of an allergic reaction. Restart the infusion at a slower rate once the patient is stabilized. It is not usually necessary to discontinue acetylcysteine.

MISCELLANEOUS

For acute acetaminophen overdose, acetylcysteine should be initiated within 24 hours, and preferably within 8 hours of acetaminophen ingestion, to prevent liver damage.

Matthew-Rumack nomogram

Matthew-Rumack nomogram image