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
Intravenous
- Loading Dose: 150 mg/kg acetylcysteine IV in 200 mL D5W over 60 minutes immediately followed by:
- Second Infusion: 50 mg/kg acetylcysteine IV in 500 mL D5W over 4 hours, immediately followed by:
- Third Infusion: 100 mg/kg acetylcysteine IV in 1000 mL D5W over 16 hours.
- At completion of the 21-hour protocol if there is a positive acetaminophen level, an INR greater than 1.5, or elevated AST or ALT, continuation of the “Third Infusion” is required. Duration will depend on multiple clinical and laboratory parameters and should be discussed with the IWK Regional Poison Centre at 1-800-565-8161.
|
Body |
Loading dose |
2nd Infusion |
3rd Infusion |
|
20% Acetylcysteine solution (mL) |
20% Acetylcysteine solution (mL) |
20% Acetylcysteine solution (mL) |
|
|
40-50 |
38 |
13 |
25 |
|
51-60 |
45 |
15 |
30 |
|
61-70 |
53 |
18 |
35 |
|
71-80 |
60 |
20 |
40 |
|
81-90 |
68 |
23 |
45 |
|
91-100 |
75 |
25 |
50 |
|
101-110 |
83 |
28 |
55 |
* Increased from 15 minutes to 1 hour to reduce the risk of anaphylactoid reactions
Oral
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
- At completion of the protocol if there is a positive acetaminophen level, an INR greater than 1.5, or elevated AST or ALT, 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 902-470-8161 or 1-800-565-8161.
|
Example calculation of dilution for oral dosing for a 70 kg person: |
|
Loading dose: |
|
NAC 20%: 0.7 ml/kg (140 mg/kg) x 70 kg = 49 ml |
|
Soda/Juice: 2 ml/kg x 70 kg = 140 ml |
|
Total volume to administer: 49 ml + 140 ml = 189 ml |
ADMINISTRATION
- Infusion: Small or large Volume parenteral (SVP, LVP).
- Infusion: Further dilute dose in D5W and administer according to protocol. NS may be used to dilute acetylcysteine for prevention of RCIN and when D5W is inappropriate.
- Infusion: Infusion device is required.
COMPATIBILITY, STABILITY
Stable for 24 hours diluted in D5W or NS at room temperature.
POTENTIAL HAZARDS OF ADMINISTRATION
- Nausea, vomiting.
- Anaphylactoid reactions (intravenous dosing). 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 (i.e. reduce the rate of infusion by half). 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
