N-acetylcysteine (NAC)
Pronunciation: en-a-seet-il-SIS-teen
“Knack, Ace of assisting”
What it isGlutathione precursor and mucolytic; acetaminophen overdose and thick respiratory secretions.
Why this oneIt restores hepatic glutathione and is fully protective when started within eight hours of acetaminophen overdose.
What limits itIV infusion can cause rate-related anaphylactoid reactions rather than true allergy. The oral form smells of sulfur.
FDA-approved for
- acetaminophen overdose (~1985)
- mucolytic (~1963)
Off-label
- trichotillomania
- contrast nephropathy prophylaxis
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Acetaminophen overdose - prevent/lessen hepatic injury (acute ingestion or repeated supratherapeutic ingestion) | Adults and pediatric patients >=5 kg | Loading 150 mg/kg IV over 1 h | then 50 mg/kg over 4 h, then 100 mg/kg over 16 h | 300 mg/kg total over 21 h (3 doses) |
Renal Undefined
Hepatic Undefined
Total 300 mg/kg over 21 h as 3 doses; consider continued treatment beyond 21 h if acetaminophen still detectable or ALT/AST/INR still rising (massive overdose, coingestants, or preexisting liver disease).
Instructions
- IV only; hyperosmolar (2600 mOsmol/L) - dilute in sterile water, 0.45% NaCl, or D5W (0.45% NaCl preferred) before infusion
- Reduce total volume for patients <40 kg or requiring fluid restriction to avoid fluid overload
- Administer as 3 sequential bags: 150 mg/kg over 1 h, then 50 mg/kg over 4 h, then 100 mg/kg over 16 h
Available strengths
- inj 200 mg/mL
- sol 10, 20 %
- inhaler 100, 200 mg/mL
Cautions
- Serious acute hypersensitivity/anaphylactoid reactions (fatal/life-threatening anaphylaxis, hypotension, wheezing, bronchospasm, rash) - most common during the loading dose; stop infusion and treat, may carefully restart after resolution
- Monitor asthmatic patients closely
- Fluid overload (can cause hyponatremia, seizure, death) - adjust total volume for <40 kg or fluid restriction
Adverse reactions
- Rash
- Urticaria/facial flushing
- Pruritus
Pregnancy Limited human data insufficient to inform risk; delaying treatment of acetaminophen overdose may increase maternal/fetal morbidity and mortality; no adverse developmental effects in animals.
Lactation No data on presence in human milk; nearly completely cleared 30 h after administration; may pump and discard milk for 30 h after dosing.
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 200 mg/mL | inj | per unit | not offered |
Other forms: Acetylcysteine (ACETADOTE)
NO BOXED WARNINGS
Principal riskAnaphylactoid infusion reactions, usually rate-related
Classes and tags
Clinical profile
Defining liabilityInhaled bronchospasm; oral gastrointestinal intolerance
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