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acetylcysteine

V03AB23

Forms & Strengths

Oral tablets 600 mg
Effervescent tablets 600 mg (reconstituted)
Oral solution 20 % (200 mg/mL)
IV solution 20 % (200 mg/mL)
IV solution 10 % (100 mg/mL)
Nebulized solution 3–5 mL of 20 % per dose

Adult Dosing

Acetaminophen overdose PO: 140 mg/kg loading, then 70 mg/kg q4h for 17 doses (total 300 mg/kg)
Acetaminophen overdose IV: 150 mg/kg over 15–60 min, then 50 mg/kg over 4 h, then 100 mg/kg over 16 h
Mucolytic PO: 600 mg q6h (max 3 g/24 h) or 3–6 g divided q6h
Nebulized: 3–5 mL of 20 % solution 3–4 times daily
Contrast‑induced nephropathy prophylaxis PO: 1200 mg BID starting 2 h before contrast and continued for 2 days

Pediatric Dosing

Acetaminophen overdose PO: 140 mg/kg loading, then 70 mg/kg q4h for 17 doses (max 100 mg/kg per dose)
Acetaminophen overdose IV: 140 mg/kg over 1 h, then 70 mg/kg over 4 h, then 140 mg/kg over 16 h (weight‑based)
Mucolytic PO: 70–140 mg/kg/day divided q6h (max 600 mg per dose)
Nebulized: 0.15 mL/kg of 20 % solution q6h (max 5 mL per dose)
Contrast prophylaxis PO: 120 mg/kg BID 2 days before and after contrast (max 1200 mg per dose)

Indications

Acetaminophen (paracetamol) overdose
Mucolytic therapy for chronic bronchitis, COPD, cystic fibrosis, and sinusitis
Prevention of contrast‑induced nephropathy
Adjunct in severe influenza or viral pneumonia with oxidative stress
Management of acetaminophen poisoning in combination with activated charcoal

Mechanism of Action

Provides cysteine for hepatic glutathione synthesis, detoxifying N‑acetyl‑p‑benzoquinone imine (NAPQI)
Restores intracellular antioxidant capacity, reducing oxidative injury
Breaks disulfide bonds in mucous glycoproteins, decreasing viscosity
Scavenges free radicals and modulates inflammatory cytokines

Contraindications

Known hypersensitivity to N‑acetylcysteine or its excipients
Severe active bronchospasm (inhaled route may precipitate bronchoconstriction)
Caution in patients with severe hepatic failure (dose adjustment only, not absolute contraindication)

Adverse Reactions

Nausea, vomiting, abdominal discomfort
Rash, urticaria, pruritus
Anaphylactoid reactions with IV administration (flushing, hypotension, bronchospasm)
Metallic taste, oral irritation
Rare: angioedema, elevated liver enzymes

Drug Interactions

Activated charcoal may reduce oral NAC absorption – separate administration by ≥2 h
Concurrent nitroglycerin or other vasodilators may enhance hypotensive effect
Potential reduction of anticoagulant effect of warfarin (monitor INR if long‑term use)
High-dose NAC may increase the renal clearance of certain antibiotics (e.g., aminoglycosides) – monitor levels
No clinically significant interaction with acetaminophen when used for overdose reversal

Curated Content: Needs Vetting Before Put to Clinical Use