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(C) Vancouver
General Hospital.
This monograph may not be reproduced without permission.
For further information, please contact a Pharmacist. |
NAME OF DRUG
acetylcysteine
CLASSIFICATION
Antidote
ALTERNATE NAME
MUCOMYST
INDICATIONS
- antidote to prevent or lessen hepatic injury due to acetaminophen overdose
RECONSTITUTION AND STABILITY
- stable 24 hours under refrigeration
- stable 20 hours at room temperature during infusion
COMPATIBILITY
- compatible with NS, D5W only (D5W preferred diluent for
acetaminophen overdose)
- incompatible with other drugs
ROUTES OF ADMINISTRATION
- IV intermittent - over 1 hour
- IV infusion - D5W recommended infusion solution for
acetaminophen overdose
VH & HSC ADMINISTRATION POLICY
A - Not to be administered by the direct IV route
DOSAGE
Initial dose of 150 mg/kg over 1 hour, followed by 50 mg/kg over 4 hours and 100 mg/kg
over the next 16 hours.
Amount of a 20% (200mg/mL) acetylcysteine solution required
(mLs)
| Body Weight (kg) |
Initial infusion: in 200mL D5W
over 1 hour |
2nd infusion: in 500mL D5W over 4
hours |
3rd infusion: in 1000mL D5W over
16 hours |
| 40 - 50 |
37.5 |
12.5 |
25.0 |
| 50 - 60 |
45.0 |
15.0 |
30.0 |
| 60 - 70 |
52.5 |
17.5 |
35.0 |
| 70 - 80 |
60.0 |
20.0 |
40.0 |
| 80 - 90 |
67.5 |
22.5 |
45.0 |
| 90 - 100 |
75.0 |
25.0 |
50.0 |
| 100 - 110 |
82.5 |
27.5 |
55.0 |
Alternate method: Initial dose of 140mg/kg over 1 hour, followed by 70mg/kg over 1 hour
q4h x 12 doses
POTENTIAL HAZARDS OF PARENTERAL ADMINISTRATION
- bronchospasm and anaphylaxis, although rare, have been reported
- skin rash, hives and fever
- nausea, vomiting, flushing
- minor transient rise in BP
IMPORTANT IMPLICATIONS
- N-acetylcysteine therapy should be started within 24 hours and preferably within10 hrs
of acetaminophen ingestion; however therapy is effective even if given after 24 hours
- patients who present late (ie. > 10 hours after overdose) may require larger or
prolonged doses of N-acetylctsteine; it is advised to contact the Poison Centre for advice
on the best management for these patients (682-5050)
- acetaminophen reaches peak serum concentrations at 4 hours; serum levels taken before 4
hours may underestimate risk of hepatotoxicity
- the following plasma levels of acetaminophen, related to hours post ingestion, are
associated with hepatic toxicity:
| Plasma level umol/L (mcg/mL) |
Hours post-ingestion |
| 993 (150) |
4 |
| 464 (70) |
8 |
| 132 (20) |
15 |
| 26 (4) |
24 |
- acetylcysteine should be continued in patients with these or higher concentrations of
acetaminophen in plasma
- concomitant alcohol or barbiturate ingestion may increase the formation of toxic
metabolites; in these instances, blood levels of acetaminophen may underestimate the true
risk of hepatotoxicity
- monitor liver function for 7 days in symptomatic patients
- monitor and treat as necessary for hypoglycemia
Revised March 2005