Acetylcysteine exerts its effects through multiple mechanisms, depending on its clinical use:

1. Mucolytic Action:
   • Acetylcysteine breaks disulfide bonds in mucoproteins, reducing the viscosity of mucus in the respiratory tract.
   • This makes it easier to clear secretions from the airways, improving breathing in conditions like chronic obstructive pulmonary disease (COPD) and cystic fibrosis.
2. Antioxidant Action:
   • Acetylcysteine is a precursor to glutathione, a potent antioxidant that neutralizes free radicals and reactive oxygen species (ROS).
   • By replenishing glutathione levels, acetylcysteine protects cells from oxidative stress and damage.
3. Antidote for Acetaminophen Overdose:
   • In cases of acetaminophen (paracetamol) overdose, acetylcysteine prevents liver damage by binding to the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI) and replenishing glutathione stores.
4. Renal Protection:
   • Acetylcysteine may reduce the risk of contrast-induced nephropathy (kidney damage) in patients undergoing imaging studies with iodinated contrast agents.

Acetylcysteine is used for the following conditions:

1. Respiratory Conditions:
   • Chronic Obstructive Pulmonary Disease (COPD): Reduces mucus viscosity, improving airway clearance.
   • Cystic Fibrosis: Helps manage thick, sticky mucus in the airways.
   • Bronchiectasis: Aids in clearing excessive mucus.
2. Acetaminophen Overdose:
   • Prevents or reduces liver damage caused by toxic metabolites of acetaminophen.
3. Contrast-Induced Nephropathy:
   • Reduces the risk of kidney damage in patients receiving iodinated contrast media.
4. Psychiatric and Neurological Disorders (Off-Label):
   • Used as an adjunct in conditions like bipolar disorder, obsessive-compulsive disorder (OCD), and neurodegenerative diseases due to its antioxidant properties.
5. Liver Protection:

May be used in other forms of drug-induced liver injury or non-acetaminophen-related liver failure.

The dosage of acetylcysteine varies depending on the condition being treated. Always follow the prescribing physician’s instructions.

Common Dosages:

• Acetaminophen Overdose:
  • IV Route: 150 mg/kg in 200 mL of 5% dextrose over 15–60 minutes, followed by 50 mg/kg in 500 mL over 4 hours, then 100 mg/kg in 1000 mL over 16 hours.
  • Oral Route: 140 mg/kg initially, followed by 70 mg/kg every 4 hours for 17 doses.
• Respiratory Conditions:
  • Inhalation: 1–10 mL of 10% or 20% solution nebulized 3–4 times daily.
  • Oral: 200–600 mg 2–3 times daily.
• Contrast-Induced Nephropathy:
  • Oral: 600–1200 mg twice daily, starting the day before and continuing on the day of the procedure.
  • IV: 600–1200 mg before and after the procedure.

Administration Tips:

• For inhalation, use a nebulizer and follow proper cleaning instructions to prevent contamination.
• For IV administration, ensure proper dilution to avoid adverse reactions.

Oral formulations should be taken with plenty of water to prevent gastrointestinal irritation.

Acetylcysteine is generally well-tolerated, but some patients may experience side effects:

Common Side Effects:

• Inhalation:
  • Bronchospasm (especially in asthmatics)
  • Stomatitis (mouth irritation)
  • Rhinorrhea (runny nose)
• Oral/IV:
  • Nausea and vomiting
  • Diarrhea
  • Skin rash or itching

Rare but Serious Side Effects:

• Anaphylaxis: Severe allergic reactions, particularly with IV administration.
• Bronchospasm: Severe airway constriction, especially in asthmatics.
• Hepatotoxicity: Rare cases of liver dysfunction.

If severe side effects occur, discontinue use and seek immediate medical attention.

Before using acetylcysteine, inform your healthcare provider if you have:

• Asthma or a history of bronchospasm
• Peptic ulcer disease (for oral formulations)
• Liver or kidney disease
• Allergies to acetylcysteine or any component of the formulation

Special Populations:

• Pregnancy: Generally considered safe when used for acetaminophen overdose or respiratory conditions. Consult a healthcare provider for other uses.
• Breastfeeding: Limited data; use only if clearly needed.
• Elderly Patients: Use with caution due to potential renal or hepatic impairment.

Acetylcysteine may interact with other medications, altering their effects:

1. Activated Charcoal:
   • Reduces the absorption of oral acetylcysteine when used for acetaminophen overdose. Administer acetylcysteine first, followed by charcoal if needed.
2. Nitroglycerin:
   • Concurrent use may cause severe hypotension and headaches.
3. Anticoagulants:
   • Acetylcysteine may enhance the effects of blood thinners like warfarin, increasing the risk of bleeding.
4. Antihypertensives:
   • May potentiate the blood pressure-lowering effects of antihypertensive drugs.
5. Contrast Media:

Acetylcysteine is used to reduce the risk of contrast-induced nephropathy but may interact with other medications administered during imaging

• Acetylcysteine
• N-acetylcysteine (NAC)