Acetylcysteine Schedule (India)

Schedule H

Acetylcysteine Routes

Oral, Intravenous, Inhalation

Acetylcysteine Formulations

Effervescent tablets: 600 mg

Oral granules/sachets: 100 mg, 200 mg, 600 mg (for oral solution)

Injection: 200 mg/mL (10 mL vial — 2000 mg)

Injection: 200 mg/mL (25 mL vial — 5000 mg)

Nebuliser solution: 10% w/v (100 mg/mL)

Nebuliser solution: 20% w/v (200 mg/mL)

Acetylcysteine Adult indications

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

Paracetamol (Acetaminophen) Poisoning — Antidote — Adults

Intravenous Protocol (Preferred — 21-hour regimen):

Phase Dose Diluent Infusion Time

Loading dose 150 mg/kg 200 mL 5% Dextrose Over 1 hour

First maintenance 50 mg/kg 500 mL 5% Dextrose Over 4 hours

Second maintenance 100 mg/kg 1000 mL 5% Dextrose Over 16 hours

Total dose 300 mg/kg — Over 21 hours

Clinical Notes:

Initiate within 8 hours of ingestion for maximum hepatoprotection; still beneficial up to 24 hours or later if hepatotoxicity present

Use Rumack-Matthew nomogram to assess need for NAC in acute single ingestion (plot serum paracetamol level against time since ingestion)

Continue beyond 21 hours if INR elevated, rising transaminases, or ongoing hepatotoxicity — consult toxicology/hepatology

Dilute ONLY in 5% Dextrose — do not use normal saline

Oral Protocol (Alternative when IV not feasible):

Parameter Recommendation

Starting dose (Loading) 140 mg/kg orally

Titration Not applicable

Usual maintenance dose 70 mg/kg every 4 hours × 17 doses

Maximum dose Total 1330 mg/kg over 72 hours

Clinical Notes:

Dilute in cola, juice, or water to improve palatability and reduce vomiting

If vomiting occurs within 1 hour of dose, repeat that dose

Less preferred due to high emesis rate; reserve for settings where IV unavailable

Mucolytic Therapy (Chronic Bronchitis, COPD, Bronchiectasis) — Adults

Oral Route:

Parameter Recommendation

Starting dose 600 mg orally once daily

Titration May increase to twice daily if tolerated and needed

Usual maintenance dose 600 mg once or twice daily

Maximum dose 1200 mg/day

Duration: Long-term use acceptable; reassess efficacy periodically

Inhalation Route (Nebulised):

Parameter Recommendation

Starting dose 3–5 mL of 10% solution OR 1–2 mL of 20% solution via nebuliser

Titration Adjust frequency based on sputum viscosity

Usual maintenance dose 3–5 mL of 10% solution 3–4 times daily

Maximum dose 20 mL of 10% solution per day in divided doses

Clinical Notes:

Pre-treatment with bronchodilator (salbutamol) recommended to reduce bronchospasm risk

May be diluted with normal saline if irritation occurs

Direct instillation via tracheostomy: 1–2 mL of 10–20% solution every 1–4 hours

Cystic Fibrosis — Mucolytic — Adults

Parameter Recommendation

Starting dose 3–5 mL of 10% solution via nebuliser twice daily

Titration Adjust frequency based on response

Usual maintenance dose 3–5 mL of 10% solution 2–4 times daily

Maximum dose 20 mL of 10% solution per day

Clinical Notes:

Use as part of comprehensive airway clearance regimen

Dornase alfa (rhDNase) is often preferred mucolytic in CF where available

Secondary Indications — Adults (Off-label)

Indication Dose Duration Notes

Contrast-Induced Nephropathy Prevention 600–1200 mg orally twice daily Start 24 hours before contrast; continue for 24–48 hours after OFF-LABEL • Evidence conflicting; benefit uncertain • Not routinely recommended in current guidelines • Consider in high-risk patients (eGFR <45, diabetes) with adequate hydration

Non-Alcoholic Fatty Liver Disease (NAFLD) 600 mg orally twice daily 3–6 months OFF-LABEL • Specialist only • Antioxidant effect • Limited Indian data

Acute Respiratory Distress Syndrome (ARDS) — Adjunct 40–150 mg/kg/day IV in divided doses ICU setting; variable duration OFF-LABEL • Specialist/ICU only • Variable protocols • Limited evidence

Acetylcysteine Paediatric indications

PAEDIATRIC DOSING (Specialist Only)

Primary Indications (Approved / Standard in India)

Paracetamol Poisoning — Antidote

Intravenous Protocol:

Weight Category Loading Dose First Maintenance Second Maintenance

<20 kg 150 mg/kg in 3 mL/kg 5% Dextrose over 1 hour 50 mg/kg in 7 mL/kg 5% Dextrose over 4 hours 100 mg/kg in 14 mL/kg 5% Dextrose over 16 hours

20–40 kg 150 mg/kg in 100 mL 5% Dextrose over 1 hour 50 mg/kg in 250 mL 5% Dextrose over 4 hours 100 mg/kg in 500 mL 5% Dextrose over 16 hours

40 kg Adult volumes and dosing Adult volumes Adult volumes

Clinical Notes:

Total dose: 300 mg/kg over 21 hours (same as adults)

Volume reduction critical in children <20 kg to prevent fluid overload

Continue if hepatotoxicity evident; consult paediatric toxicology

Oral Protocol (Alternative):

Parameter Recommendation

Starting dose (Loading) 140 mg/kg orally

Usual maintenance dose 70 mg/kg every 4 hours × 17 doses

Maximum dose Total 1330 mg/kg over 72 hours

Mucolytic Therapy — Inhalation

Age-Based Dosing:

Age Group	Dose (mcg/kg/day)	Typical Total Daily Dose	Clinical Notes

2–6 years 3 mL of 10% solution via nebuliser 2–3 times daily Specialist supervision; pre-treat with bronchodilator

6–12 years 3–5 mL of 10% solution via nebuliser 2–4 times daily Pre-treat with bronchodilator

12 years Adult dosing 3–4 times daily —

Safety Monitoring:

Monitor for bronchospasm — have bronchodilator available

Suction equipment should be available if child cannot expectorate

Observe for increased sputum production

Secondary Indications — Paediatric (Off-label)

Not applicable — No routinely accepted off-label paediatric uses in Indian practice.

Age Restrictions:

Nebulised acetylcysteine: Not recommended in children <2 years except under specialist supervision due to risk of bronchospasm and inability to clear increased secretions

Oral mucolytic use: Limited data in children; avoid routine use below 2 years

IV antidote use: No minimum age — use for paracetamol poisoning in any age group

Acetylcysteine Renal Adjustments

No dose adjustment required for any indication.

Notes:

Acetylcysteine is not significantly renally excreted

Safe in renal impairment including dialysis patients

For paracetamol poisoning in dialysis patients: administer as per standard protocol; drug not significantly removed by dialysis

Acetylcysteine Hepatic adjustment

Severity	Recommendation
Mild impairment	No dose adjustment required
Moderate impairment	No dose adjustment required
Severe impairment	/ Acute liver failure No dose reduction — acetylcysteine is the treatment for paracetamol-induced hepatotoxicity; continue full protocol

Notes:

In paracetamol poisoning with hepatic failure, IV fluid volumes may need adjustment to prevent fluid overload

Continue NAC until INR normalising and transaminases declining

Acetylcysteine Contraindications

Known hypersensitivity to acetylcysteine

Severe uncontrolled asthma (for inhaled route) — risk of severe bronchospasm

Previous anaphylactoid reaction to IV acetylcysteine requiring permanent discontinuation

Note: For paracetamol poisoning, there are no absolute contraindications — benefit of preventing hepatic failure outweighs risks.

Acetylcysteine Cautions

Bronchial asthma — inhaled and IV routes may trigger bronchospasm; pre-treat with bronchodilator; have emergency treatment available

History of peptic ulcer disease — oral acetylcysteine may cause GI irritation

Fluid overload risk — large IV volumes in 21-hour protocol; monitor in cardiac failure, renal failure, or low body weight

Anaphylactoid reactions — common with IV route (up to 10–20%); usually manageable without stopping infusion

Inability to protect airway or expectorate — inhaled route may increase secretions dangerously

Patients <40 kg or <20 kg — adjust IV fluid volumes to prevent hyponatraemia or fluid overload

Acetylcysteine Pregnancy

Parameter Information

Risk Category Generally considered safe (limited human data; animal studies reassuring)

Overall Safety Benefits outweigh risks, especially for paracetamol poisoning

Preferred Alternatives None — acetylcysteine is the treatment of choice for paracetamol overdose in pregnancy

When May Be Used Essential for paracetamol poisoning at any stage of pregnancy; mucolytic use if clearly indicated

Monitoring Maternal LFTs, INR in overdose; standard antenatal monitoring; fetal wellbeing in significant overdose

Note: Untreated paracetamol poisoning carries high fetal and maternal mortality — do not delay NAC due to pregnancy.

Acetylcysteine Lactation

Parameter Information

Compatibility Compatible with breastfeeding

Expected Milk Levels Low — minimal systemic absorption with oral mucolytic doses; short half-life

Preferred Alternatives None needed for indicated uses

Decision Continue breastfeeding; no interruption required

Infant Monitoring Observe for irritability, GI upset (unlikely)

Acetylcysteine Elderly

Parameter Recommendation

Starting dose Standard adult dosing for all routes

Titration Standard titration

Special considerations Higher risk of fluid overload with IV protocol in patients with cardiac failure

Extra monitoring Fluid balance; renal function; cardiac status during IV infusion

Risk factors Pre-existing cardiac disease; reduced renal reserve

Acetylcysteine Major drug interactions

Interacting Drug Effect & Mechanism Management

Activated charcoal Adsorbs oral acetylcysteine — reduces absorption by up to 30% Separate doses by at least 2 hours; if both indicated for paracetamol overdose, give charcoal first, then IV NAC preferred

Nitrates (nitroglycerin, isosorbide) Additive vasodilation — may cause significant hypotension Monitor blood pressure if used concurrently; use with caution

Acetylcysteine Moderate drug interactions

Interacting Drug Effect Management

Carbamazepine Hepatotoxic paracetamol metabolite production may be increased in carbamazepine users — lower threshold for NAC Use standard NAC protocol; may need treatment at lower paracetamol levels

Phenytoin, Phenobarbital Enzyme induction increases toxic metabolite of paracetamol Lower threshold for NAC treatment

Isoniazid Increased paracetamol hepatotoxicity risk Be vigilant; use NAC at lower threshold if overdose suspected

Antitussives May reduce cough reflex needed to clear increased secretions from mucolytic effect Avoid concurrent use with inhaled acetylcysteine

Laboratory Interference:

May cause false results in colorimetric assays for salicylates, glucose, and uric acid

Use enzymatic glucose assays in diabetic patients receiving acetylcysteine

Acetylcysteine Common Adverse effects

Intravenous Route:

Anaphylactoid reactions (flushing, urticaria, pruritus, angioedema) — up to 10–20%

Nausea and vomiting

Hypotension (usually transient)

Bronchospasm (especially in asthmatics)

Oral Route:

Nausea and vomiting (common — due to sulfur odour and taste)

Diarrhoea

Abdominal discomfort

Unpleasant sulfurous odour ("rotten egg" smell)

Inhalation Route:

Bronchospasm

Cough

Rhinorrhoea

Nausea

Stomatitis

Increased secretions

Acetylcysteine Serious Adverse effects

Adverse Effect Clinical Action

Anaphylactoid reaction (urticaria, angioedema, bronchospasm, hypotension) Temporarily pause infusion; give IV antihistamine (chlorpheniramine) ± hydrocortisone; restart at slower rate once symptoms controlled — rarely requires permanent discontinuation

Severe bronchospasm Stop infusion/inhalation; bronchodilator therapy; oxygen; consider adrenaline if severe

Severe hypotension Stop infusion; IV fluids; vasopressors if needed

Anaphylaxis (true IgE-mediated — extremely rare) Permanent discontinuation; standard anaphylaxis management

Note: Most IV reactions are anaphylactoid (non-IgE mediated) and do not preclude continued treatment after symptom management.

Acetylcysteine Monitoring requirements

For Paracetamol Poisoning:

Timing	Parameters
Baseline	Serum paracetamol level (4 hours post-ingestion minimum); LFTs (AST, ALT); INR/PT; serum creatinine; blood glucose; arterial blood gas if severe

During IV infusion Vital signs (especially for anaphylactoid reactions); hourly during loading dose

Serial monitoring LFTs, INR, creatinine — every 12–24 hours until improving

End of protocol Repeat LFTs, INR — continue NAC if still abnormal

For Mucolytic Therapy:

Timing	Parameters
Baseline	Respiratory status; ability to expectorate

During therapy Monitor for bronchospasm; sputum clearance; respiratory comfort

Long-term Periodic assessment of symptom improvement

Acetylcysteine Brands in India

Oral/Effervescent:

Mucinac (Cipla)

NAC (Samarth)

Fluimucil (Zambon)

Acemiz (Systopic)

Mucyst (Torrent)

Nacfil (Cipla)

Mucox (FDC)

Injectable:

Mucinac Injection (Cipla)

NAC Injection (various manufacturers)

Fluimucil Injection (Zambon)

Nebuliser Solution:

Mucomix (Cipla)

Mucinac Respules (Cipla)

Fluimucil Nebuliser Solution (Zambon)

FDCs Available:

Acetylcysteine + Ambroxol

Acetylcysteine + Levosalbutamol

(Use only if specifically indicated; monotherapy preferred for dose titration)

Acetylcysteine Price range (INR)

Formulation	Approximate Price (per tablet)
Effervescent tablet 600 mg ₹12–₹25 per tablet
Oral sachet 600 mg ₹10–₹20 per sachet
Injection 200 mg/mL (10 mL vial) ₹120–₹180 per vial
Injection 200 mg/mL (25 mL vial) ₹250–₹400 per vial
Nebuliser solution 10% (3 mL) ₹25–₹40 per ampoule

Note: Injection (for paracetamol poisoning) included in NLEM 2022 — may be NPPA price-controlled. Available in government hospitals for toxicology emergencies.

Acetylcysteine Clinical pearls

IV route is preferred for paracetamol poisoning — oral NAC has high emesis rate and erratic absorption after overdose; reserve oral for settings without IV access

Dilute IV NAC only in 5% Dextrose — not normal saline; ensures stability and prevents precipitation

Anaphylactoid reactions are common but manageable — do not abandon NAC therapy for mild-moderate reactions; pause infusion, treat with antihistamines ± steroids, and resume at slower rate

Use Rumack-Matthew nomogram — plot paracetamol level against time post-ingestion (minimum 4 hours) to determine NAC indication; if time of ingestion unknown or staggered overdose, treat empirically

Don't confuse formulations — injectable acetylcysteine is NOT interchangeable with nebuliser or oral solutions; each has specific concentration and use

Pre-treat with bronchodilator before nebulised NAC — reduces bronchospasm risk, especially in asthmatics and COPD patients

Acetylcysteine Tags

Acetylcysteine; N-acetylcysteine; NAC; antidote; paracetamol poisoning; acetaminophen overdose; mucolytic; glutathione precursor; emergency medicine; NLEM India; asthma-caution; pregnancy-safe

Acetylcysteine Version

RxIndia v1.0 — 05 Jan 2025

Acetylcysteine Reference

CDSCO Approved Drug Formulations Database

Indian Pharmacopoeia 2022

National Formulary of India 2021

NLEM 2022

AIIMS Emergency Medicine Handbook / Toxicology Protocols

API Textbook of Medicine, 11th Edition

ICMR Guidelines for Poisoning Management

Harrison's Principles of Internal Medicine, 21st Edition

Goodman & Gilman's The Pharmacological Basis of Therapeutics

WHO Model List of Essential Medicines

Indian critical care and pulmonology protocols

RxIndia

The Drug Registry

Acetylcysteine