Mucolysin (Acetylcysteine)

Mucolysin (acetylcysteine) is used as a mucolytic therapy for disorders that involve thickened respiratory secretions.

• Chronic obstructive pulmonary disease (COPD): facilitates clearance of viscous sputum and improves airflow.
• Cystic fibrosis: lowers mucus viscosity to aid expectoration and reduce airway obstruction.
• Acute bronchitis: promotes expectoration of secretions, easing cough and breathing.
• Bronchopulmonary infections: enhances mucus clearance, supporting antimicrobial treatment.

• Acetylcysteine acts by cleaving disulfide bonds within mucopolysaccharide chains of mucus, thereby breaking down the polymeric network that gives mucus its high viscosity. This depolymerisation reduces mucus thickness, allowing ciliary action and cough to more effectively transport secretions out of the airways, improving ventilation and gas exchange.

Acetylcysteine is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Nausea: mild to moderate stomach upset after oral intake.
• Vomiting: occasional emesis, especially with higher doses.
• Taste disturbance: a characteristic sulfurous or metallic taste.
• Abdominal discomfort: cramping or mild pain.
• Headache: transient mild headache.
• Rash: mild skin erythema or pruritus.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction with airway compromise.
• Stevens‑Johnson syndrome: rare severe skin eruption.
• Bronchospasm: worsening airway constriction, especially in asthmatics.
• Hepatic dysfunction: elevated liver enzymes in susceptible individuals.
• Hemolysis: rare breakdown of red blood cells, noted in patients with G6PD deficiency.

When prescribing acetylcysteine, clinicians should consider several safety measures.

• Renal function assessment: adjust use in patients with severe renal impairment.
• Hepatic monitoring: observe liver enzymes in patients with existing liver disease.
• Bronchospasm risk: avoid rapid inhalation in asthmatic patients prone to bronchospasm.
• Hypersensitivity: discontinue if signs of allergic reaction appear.
• Elderly patients: start with lower doses and monitor tolerance.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Acetylcysteine may interact with other medicines, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Nitroprusside: concurrent use can potentiate hypotensive effects.
• Cyclophosphamide: may increase cytotoxicity and risk of organ toxicity.
• Anticoagulants (e.g., warfarin): heightened bleeding risk due to altered platelet function.

Moderate Interactions (Monitor Closely)

• Nitroglycerin: possible additive hypotensive effect.
• Theophylline: acetylcysteine may affect serum levels, requiring monitoring.
• Alcohol: combined use can increase gastrointestinal irritation and discomfort.