acetylcysteine
Brand: Mucomyst, Acetadote
Prototype Drug
Drug Class: mucolytic / antidote
Drug Family: mucolytic/expectorant
Subclass: cysteine precursor (glutathione replenisher) / direct mucolytic
Organ Systems: respiratorytoxicology
Mechanism of Action
Cleaves disulfide bonds in glycoprotein polymers of mucus (inhaled mucolytic); also provides cysteine for hepatic glutathione synthesis — counteracting NAPQI hepatotoxicity in acetaminophen overdose.
mucus disulfide bonds (mucolytic)hepatic glutathione replenishment (antidote)
Indications
- acetaminophen overdose (IV/oral) — PRIORITY USE
- mucolytic in cystic fibrosis/bronchiectasis
- COPD exacerbation (inhaled)
- contrast nephropathy prevention (limited evidence)
Contraindications
- active bronchospasm (inhaled form — can trigger)
Adverse Effects
Common
- nausea and vomiting (oral)
- bronchospasm (inhaled)
- flushing
- urticaria (IV anaphylactoid)
Serious
- anaphylactoid reaction (IV)
- bronchospasm
Pharmacokinetics (ADME)
| Absorption | inhalation: local; IV/oral: systemic |
| Distribution | hepatic distribution (IV) |
| Metabolism | hepatic |
| Excretion | renal |
| Half-life | 6.25 hours |
| Onset | immediate IV |
| Peak | 1-3 hours (oral) |
| Duration | variable |
| Protein Binding | 83% (bound) |
| Vd | 0.47 L/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| charcoal (acetaminophen OD) | charcoal may reduce oral acetylcysteine absorption — timing dependent; IV preferred if charcoal given | moderate |
Nursing Considerations
- Acetaminophen overdose: IV preferred (Acetadote) — 3-bag protocol over 21 hours; oral (Mucomyst) if IV unavailable
- Calculate Rumack-Matthew nomogram to determine if treatment threshold exceeded
- IV anaphylactoid reactions (urticaria, flushing) — slow infusion or antihistamine; rarely require stopping
- Inhaled: dilute with NS; follow with bronchodilator if reactive airway disease
Clinical Pearls
- Hepatoprotection: provides cysteine to replenish glutathione which neutralizes NAPQI (toxic acetaminophen metabolite)
- Rumack-Matthew nomogram: acetaminophen level vs time of ingestion determines treatment need
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.