Dornase Alpha ✅

💊 Dornase alfa is a recombinant human deoxyribonuclease used as a nebulised mucolytic treatment in selected patients with cystic fibrosis. Dornase alfa is administered by nebuliser/inhalation. It breaks down extracellular DNA in thick airway secretions, reducing sputum viscosity and helping mucus clearance. Always check the BNF dornase alfa monograph, local formulary and specialist cystic fibrosis plan before prescribing.

ℹ️ About

• Drug name: Dornase alfa. Brand example: Pulmozyme®. Drug class: recombinant human deoxyribonuclease I.
• Main use: mucolytic therapy in cystic fibrosis.
• Formulation: nebuliser solution, commonly 2.5 mg/2.5 mL = 2500 units.
• Prescribing: usually specialist-led via a cystic fibrosis team or local shared-care arrangement.

🧬 Mode of Action

• In cystic fibrosis, airway mucus becomes thick, sticky and difficult to clear.
• Chronic neutrophilic inflammation releases large amounts of extracellular DNA into sputum.
• Dornase alfa enzymatically cleaves extracellular DNA.
• This reduces sputum viscosity, making airway secretions easier to clear with physiotherapy and coughing.
• The aim is to improve lung function and reduce respiratory infective exacerbations.

🎯 Indication

• Management of cystic fibrosis to improve pulmonary function in patients with FVC greater than 40% predicted.
• Use should be guided by a specialist cystic fibrosis team.
• It is not a general mucolytic for ordinary cough, COPD or non-CF bronchiectasis unless advised by a specialist/local formulary.

💊 Dose - Always Check BNF / Local Guidance

🫁 Administration Advice

• Give by nebuliser exactly as advised by the cystic fibrosis team.
• Do not mix dornase alfa with other medicines or solutions in the nebuliser chamber.
• Use the recommended nebuliser device and clean it according to local/device instructions.
• It is often given before airway clearance physiotherapy, but timing should follow the specialist plan.
• Store according to the product information, usually refrigerated and protected from light.
• If using several inhaled/nebulised medicines, the CF team should advise the correct order.

⚠️ Cautions

• Use under specialist supervision in cystic fibrosis.
• Assess whether symptoms worsen after nebulisation, such as bronchospasm, chest tightness or dyspnoea.
• Review if haemoptysis, acute chest infection, falling lung function or poor treatment tolerance occurs.
• Ensure the patient can use and clean the nebuliser safely.
• Check local policy for children, pregnancy, breastfeeding and shared-care prescribing.

⛔ Contraindications

• Hypersensitivity to dornase alfa or any excipient in the formulation.
• Do not use for an unlicensed indication unless advised by a specialist and local policy supports it.

🔁 Interactions

• No major clinically important drug interactions are usually expected.
• Do not physically mix with other nebulised drugs in the nebuliser chamber because compatibility is not assured.
• If the patient is also prescribed bronchodilators, hypertonic saline, inhaled antibiotics or airway clearance therapy, follow the CF team’s administration sequence.

⚕️ Side Effects

• Voice alteration or dysphonia.
• Pharyngitis or throat irritation.
• Cough or increased sputum expectoration.
• Chest discomfort or chest pain.
• Dyspnoea or bronchospasm, uncommon but clinically important.
• Conjunctivitis. Rash or skin reactions.
• Fever. Dyspepsia.

📈 Monitoring

• Symptoms, sputum burden and ease of airway clearance.
• Lung function, especially FEV1/FVC trends as directed by the CF team.
• Frequency of infective pulmonary exacerbations.
• Treatment adherence and nebuliser technique.
• Adverse effects such as dysphonia, bronchospasm, chest tightness or rash.

🚩 When to Seek Urgent Advice

• Severe breathlessness, wheeze or chest tightness after nebulisation.
• Significant haemoptysis.
• Signs of acute pulmonary exacerbation: increasing cough, sputum, fever, breathlessness or falling oxygen saturations.
• Suspected allergic reaction: swelling, urticaria, severe rash or breathing difficulty.

📝 Exam Pearls

• 🧬 Dornase alfa is recombinant human DNase.
• 🫁 It breaks down extracellular DNA in CF sputum, reducing viscosity.
• 💨 Route is nebulised inhalation, not SC, IM or oral.
• 🎯 Used in selected cystic fibrosis patients to improve pulmonary function.
• 📋 Always check the BNF and local CF specialist plan before prescribing.

🧠 Teaching Note

In cystic fibrosis, repeated airway infection and neutrophilic inflammation leave large amounts of DNA from dead inflammatory cells within sputum. That DNA acts like a thick biological glue, increasing mucus viscosity and impairing airway clearance. Dornase alfa cuts this extracellular DNA into smaller fragments, making sputum less sticky and easier to clear. This is why it is paired with physiotherapy and airway clearance rather than used as a simple cough medicine.

📚 References

• BNF/NICE – Dornase alfa
• BNFC/NICE – Cystic fibrosis treatment summary
• NICE NG78 – Cystic fibrosis: diagnosis and management
• Medicines for Children – Dornase alfa for cystic fibrosis