Asthma — Med2Date

📋 Key Information Summary

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Asthma affects approximately 2.7 million Australians (~11% of the population); it is one of the most common chronic diseases managed in primary care and a leading cause of preventable hospitalisation.
Diagnosis requires evidence of variable airflow obstruction — spirometry with bronchodilator reversibility (≥12% and ≥200 mL improvement in FEV₁) is the gold standard; fractional exhaled nitric oxide (FeNO ≥40 ppb) supports eosinophilic airway inflammation.
Severity is classified post-treatment as intermittent, mild persistent, moderate persistent, or severe persistent based on symptom frequency, night-time awakening, reliever use, and lung function.
Phenotyping (eosinophilic T2-high vs non-eosinophilic T2-low) guides biologic selection and predicts corticosteroid responsiveness.
GINA stepwise management: Step 1–2 — low-dose ICS-formoterol as needed (MART) or regular low-dose ICS + as-needed SABA; Step 3 — low-dose ICS-LABA maintenance; Step 4 — medium-dose ICS-LABA ± LAMA; Step 5 — high-dose ICS-LABA + refer for biologic assessment.
Low-dose ICS-formoterol as-needed (MART approach) is now preferred at GINA Steps 1–2 over SABA-only to reduce the risk of serious exacerbations and asthma-related death.
Acute severe asthma: give oxygen to target SpO₂ 94–98%, nebulised salbutamol 5 mg every 20 min for 3 doses then 4–6-hourly, ipratropium bromide 500 µg nebulised every 20 min for 3 doses in severe attacks, and systemic corticosteroids (prednisolone 50 mg PO or hydrocortisone 200 mg IV) within 1 hour.
Life-threatening features requiring ICU: SpO₂ <92%, silent chest, cyanosis, feeble respiratory effort, confusion, exhaustion, PaCO₂ ≥45 mmHg, pH <7.35 — escalate to IV magnesium sulphate 2 g over 20 min and consider intubation.
Five biologic classes are PBS-listed for severe uncontrolled asthma (≥2 exacerbations/year despite high-dose ICS-LABA ± LAMA): omalizumab (anti-IgE), mepolizumab and reslizumab (anti-IL-5), benralizumab (anti-IL-5Rα), and dupilumab (anti-IL-4Rα) — all require authority PBS approval.
Exercise-induced bronchoconstriction (EIB) is managed with warm-up, SABA pre-exercise, and regular ICS if frequent; occupational asthma requires early identification, exposure cessation, and WorkCover notification.
In pregnancy, maintain asthma control — uncontrolled asthma poses greater fetal risk than controller medications; budesonide ICS is the preferred controller (most safety data), and montelukast is generally avoided.
Aboriginal and Torres Strait Islander Australians have 1.4–2.1 times the asthma prevalence and 2–3 times the hospitalisation rate; culturally safe care, Indigenous health worker support, and addressing environmental triggers (dust, smoke, overcrowded housing) are essential.
Annual influenza vaccination and pneumococcal vaccination are recommended; smoking cessation support is a priority in all patients with asthma.

Introduction & Australian Epidemiology

Asthma is a heterogeneous chronic inflammatory disease of the airways characterised by variable and recurring episodes of wheeze, breathlessness, chest tightness, and cough. These symptoms are associated with variable expiratory airflow limitation that is often reversible — either spontaneously or with treatment. The condition affects all ages, though onset is most common in childhood and a second peak occurs in middle age.

In Australia, asthma is a major public health burden. The Australian Bureau of Statistics National Health Survey (2022) estimates that approximately 2.7 million Australians (10.7%) currently have asthma. Key Australian epidemiological data include:

Asthma is the leading cause of preventable hospitalisation in children under 15 and among the top five chronic conditions managed in general practice nationally.
Approximately 40,000 asthma-related hospitalisations occur annually, with the highest rates in children aged 0–4 and adults over 65.
Around 400 Australians die from asthma each year (AIHW, 2023), with a disproportionate number being older adults and those with underrecognised or undertreated disease.
Prevalence is highest in Tasmania and Queensland and lowest in the Northern Territory for non-Indigenous populations; however, the reverse is true for Aboriginal and Torres Strait Islander Australians in remote areas.
Approximately 50% of Australians with asthma report poorly controlled symptoms — defined by the Asthma Control Questionnaire or frequent reliever use (>2 days/week).
The economic burden exceeds AUD 28 billion annually (including direct healthcare costs, productivity losses, and carer burden), as estimated by Asthma Australia (2023).

Asthma phenotyping has evolved considerably. The traditional approach — classifying by severity alone — has been supplemented by treatable traits and endotype-driven therapy. The key distinction is between T2-high (eosinophilic) and T2-low (neutropholic or paucigranulocytic) asthma, which has direct implications for biologic eligibility and corticosteroid responsiveness.

Diagnosis & Classification

Clinical Diagnosis

A diagnosis of asthma should be suspected in any patient presenting with episodic wheeze, breathlessness, chest tightness, or cough — particularly if symptoms are worse at night, on exercise, or with allergen exposure, and improve spontaneously or with bronchodilator therapy. Diagnosis must be confirmed objectively wherever possible; treatment should not be initiated empirically without at least one supporting objective test, except in acute presentations where treatment should not be delayed.

Spirometry with Bronchodilator Response

Spirometry is the gold-standard investigation for diagnosing airflow obstruction and demonstrating reversibility. Per NHMRC/Australian Asthma Handbook guidelines:

Obtain baseline FEV₁, FVC, and FEV₁/FVC ratio.
An FEV₁/FVC ratio below the lower limit of normal (LLN, generally <0.70 in adults) confirms airflow obstruction.
Administer 200–400 µg salbutamol via MDI + spacer and repeat spirometry after 15–20 minutes.
A positive bronchodilator response is defined as ≥12% AND ≥200 mL improvement in FEV₁ from baseline.
If baseline spirometry is normal but clinical suspicion remains, consider a bronchial provocation challenge (mannitol — Aridol® — or methacholine) to assess airway hyperresponsiveness. A PD₂₀ mannitol <155 mg or PC₂₀ methacholine <8 mg/mL is considered positive.

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Bronchial provocation with mannitol (Aridol®) is TGA-approved and available in Australia; methacholine is not TGA-registered and is only available in specialised respiratory laboratories (private availability). MBS item 11503 covers spirometry with bronchodilator response.

Fractional Exhaled Nitric Oxide (FeNO)

FeNO is a point-of-care biomarker of eosinophilic (T2-high) airway inflammation. It is measured by having the patient exhale at a steady flow rate of 50 mL/s into a portable analyser (NIOX VERO® or NObreath®).

FeNO <25 ppb (adults) or <20 ppb (children): Eosinophilic inflammation unlikely; consider non-eosinophilic causes. A low FeNO with persistent symptoms should prompt reconsideration of the diagnosis.
FeNO 25–50 ppb: Intermediate — interpret alongside clinical context, blood eosinophils, and spirometry.
FeNO >50 ppb: Strongly suggestive of eosinophilic airway inflammation; predicts good response to ICS therapy and supports biologic eligibility.
FeNO can be elevated by atopy, rhinosinusitis, and dietary nitrates; it is reduced by smoking, bronchoconstriction, and within 4 hours of SABA use.

MBS item 11506 covers FeNO measurement in Australia. It is available in most respiratory function laboratories and some specialist practices.

Other Investigations

Essential Spirometry with bronchodilator reversibility MBS 11503. Confirms variable airflow obstruction. Perform before starting controller therapy where possible.

Available FeNO (Fractional Exhaled Nitric Oxide) MBS 11506. Biomarker for eosinophilic inflammation; guides ICS initiation and biologic selection.

Available Peak expiratory flow (PEF) variability Home PEF diary over 2–4 weeks; ≥20% diurnal variability supports diagnosis. Lower specificity than spirometry.

Available Full blood count with eosinophil count Blood eosinophils ≥300 cells/µL suggest T2-high phenotype; ≥150 cells/µL acceptable for some biologics. MBS 65070.

Referral Bronchial provocation (mannitol/methacholine) When spirometry is normal but clinical suspicion is high. Available at respiratory laboratories; MBS 11505.

Available Skin prick testing / specific IgE (sIgE) Identifies allergic triggers and atopic status. Important for phenotyping and biologic selection (omalizumab).

Referral CT chest (high-resolution) Not routine. Indicated when suspecting ABPA, bronchiectasis, or other structural lung disease.

Severity Classification

Asthma severity should be assessed after the patient has been on controller therapy for at least 2–3 months. Severity reflects the minimum treatment required to maintain control. The Australian Asthma Handbook (NHMRC) classifies severity as follows:

Severity	Daytime Symptoms	Night-Time Waking	Reliever Use	Activity Limitation	FEV₁ (% predicted)
Intermittent	≤2 days/week	≤2 times/month	≤2 days/week	None	≥80%
Mild Persistent	>2 days/week but not daily	3–4 times/month	>2 days/week but not daily	Minor	≥80%
Moderate Persistent	Daily	>1 time/week but not nightly	Daily	Some limitation	60–80%
Severe Persistent	Throughout the day	Often nightly	Several times/day	Extremely limited	<60%

Phenotyping — T2-High vs T2-Low

Modern asthma management increasingly relies on endotyping to guide therapy. The distinction between type 2 inflammatory (T2-high) and non-type 2 (T2-low) phenotypes has direct therapeutic implications, particularly for biologic eligibility.

T2-High

Eosinophilic / Allergic

Blood eosinophils ≥150–300 cells/µL, FeNO ≥25 ppb, sputum eosinophils ≥2%, atopy (positive SPT/sIgE), periostin elevated. Responds to ICS and biologics.

Comprises ~50–70% of adult asthma

T2-Low

Neutrophilic / Paucigranulocytic

Low eosinophils and FeNO. Neutrophilic predominance (sputum neutrophils ≥60%) or minimal inflammation. Poor ICS response. Consider alternative diagnoses (VCD, COPD overlap).

Comprises ~30–50% of adult asthma; higher in obese/older patients

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Diagnostic caution: Always consider and exclude alternative diagnoses before confirming asthma: vocal cord dysfunction (VCD), COPD/asthma-COPD overlap (ACO), cardiac failure, bronchiectasis, allergic bronchopulmonary aspergillosis (ABPA), upper airway obstruction, and hyperventilation syndrome.

Stepwise Management

The stepwise approach to asthma management follows the Global Initiative for Asthma (GINA) 2023/2024 strategy, adapted for the Australian context by the NHMRC Australian Asthma Handbook. The goal is to achieve and maintain symptom control with the minimum effective therapy, while minimising the risk of exacerbations, fixed airflow limitation, and medication side effects.

GINA Stepwise Framework

Step 1

As-needed low-dose ICS-formoterol (preferred)

GINA preferred: budesonide-formoterol 200/6 µg (Symbicort® Turbuhaler) 1 actuation PRN. Alternative: as-needed SABA with regular low-dose ICS (200 µg budesonide or equivalent daily). SABA-only is no longer recommended by GINA as the preferred approach.

Step 2

Regular low-dose ICS + as-needed SABA, OR as-needed low-dose ICS-formoterol (MART)

Low-dose ICS: budesonide 200–400 µg/day or fluticasone propionate 100–200 µg/day. MART option: budesonide-formoterol 200/6 µg 1 actuation BD maintenance + 1 PRN (max 8 actuations/day).

Step 3

Low-dose ICS-LABA maintenance + as-needed SABA or MART

Preferred MART: budesonide-formoterol 200/6 µg 1–2 actuations BD maintenance + 1 PRN. Alternative: low-dose ICS-LABA combination (e.g., fluticasone/salmeterol 250/25 Seretide® or budesonide/formoterol Symbicort®) + as-needed SABA.

Step 4

Medium-dose ICS-LABA ± LAMA, ± LTRA

Increase ICS to medium dose: budesonide 400–800 µg/day or fluticasone propionate 250–500 µg/day. Add tiotropium (Spiriva Respimat®) 2.5 µg, 2 puffs once daily if still uncontrolled. Consider LTRA (montelukast 10 mg nocte) in allergic/eosinophilic phenotype.

Step 5

Refer for specialist assessment and biologic therapy

High-dose ICS-LABA + LAMA. Refer to respiratory specialist for biologic assessment. Assess phenotypic markers (blood eosinophils, FeNO, total IgE, sIgE). Consider low-dose oral corticosteroids (OCS) as last resort with bone protection, diabetes monitoring, and adrenal axis monitoring.

Controller Medications

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Budesonide (Pulmicort®)

AstraZeneca · ICS · Inhaled corticosteroid

Adult dose Low: 200–400 µg/day; Medium: 400–800 µg/day; High: 800–1600 µg/day (divided BD) via Turbuhaler or Rapihaler + spacer

Paediatric dose 1–5 years: 200–400 µg/day via nebuliser; 6–11 years: 200–400 µg/day via Turbuhaler; ≥12 years: adult dosing

Renal adjustment None required

PBS status ✔ PBS General Benefit

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Budesonide/Formoterol (Symbicort®)

AstraZeneca · ICS/LABA · Maintenance and MART

Adult dose 100/6 µg or 200/6 µg Turbuhaler: 1–2 actuations BD; MART: 200/6 µg 1–2 actuations BD + 1 PRN (max 8/day)

Paediatric dose 6–11 years: 100/6 µg 1–2 actuations BD; ≥12 years: adult dosing

Renal adjustment None required; use with caution in severe hepatic impairment

PBS status ✔ PBS General Benefit

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Fluticasone/Salmeterol (Seretide®)

GSK · ICS/LABA · Combination inhaler

Adult dose 50/100 or 50/250 or 50/500 Accuhaler: 1 puff BD; 25/50, 25/125, 25/250 MDI: 2 puffs BD via spacer

Paediatric dose 4–11 years: 50/100 Accuhaler 1 puff BD; ≥12 years: adult dosing

Renal adjustment None required

PBS status ✔ PBS General Benefit

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Tiotropium (Spiriva Respimat®)

Boehringer Ingelheim · LAMA · Long-acting muscarinic antagonist

Adult dose 2.5 µg (Respimat): 2 puffs once daily, added to ICS-LABA at GINA Step 4

Paediatric dose ≥6 years: 2.5 µg 2 puffs once daily (limited evidence)

Renal adjustment None required; caution in severe renal impairment (CrCl <30 mL/min)

PBS status ⚠ PBS Authority Required

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Montelukast (Singulair®)

Organon · LTRA · Leukotriene receptor antagonist

Adult dose 10 mg PO once daily (nocte)

Paediatric dose 2–5 years: 4 mg chewable tablet nocte; 6–14 years: 5 mg chewable tablet nocte; ≥15 years: adult dosing

Renal adjustment None required

PBS status ✔ PBS General Benefit

Reliever Medications

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Salbutamol (Ventolin®)

GSK · SABA · Short-acting β₂ agonist

Adult dose 100–200 µg (1–2 puffs) MDI + spacer PRN; max 8 puffs/24 hr regularly. Nebuliser: 2.5–5 mg PRN

Paediatric dose <6 years: 100–200 µg via spacer + mask PRN; 6–11 years: 100–200 µg via spacer PRN; ≥12 years: adult dosing

Renal adjustment None required

PBS status ✔ PBS General Benefit

Step-Up / Step-Down Protocols

Review every 2–3 months when initiating or changing therapy. When asthma has been well controlled for at least 3 months, consider stepping down:

Step-down from Step 3 or 4: Reduce ICS dose by 25–50% every 3 months while maintaining LABA. Do not stop ICS abruptly.
Step-down from Step 2: Reduce ICS to lowest effective dose (e.g., budesonide 100–200 µg/day). MART patients can reduce maintenance to once daily.
Discontinuing controller therapy: Consider only if symptom-free for ≥3 months on lowest-dose ICS, normal FeNO, and no risk factors for exacerbations. Continue as-needed ICS-formoterol if previously MART.
Never stop ICS completely in patients with prior life-threatening exacerbations, fixed airflow limitation, or frequent exacerbations on step-down.

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SABA-only reliance increases mortality risk. GINA 2023 emphasises that patients receiving SABA-only treatment (no ICS) have a significantly higher risk of severe exacerbations and asthma-related death. All adults and adolescents with asthma should receive ICS-containing therapy — either regularly or as-needed with ICS-formoterol.

Acute Exacerbations

Severity Assessment

Acute asthma exacerbations (asthma attacks) are characterised by progressive worsening of breathlessness, cough, wheeze, or chest tightness over hours to days, associated with a reduction in expiratory airflow. Rapid assessment using clinical features and objective measures is essential to guide treatment intensity.

Mild

Moderate Exacerbation

Increasing symptoms, reliever use >every 3–4 hours. Able to speak in sentences. SpO₂ ≥95%. RR <25/min. PEF 50–75% best or predicted. Agitated but not exhausted.

Setting: GP / ED assessment

Severe

Severe Exacerbation

Severe breathlessness at rest, cannot complete sentences. Use of accessory muscles. SpO₂ <95%. RR ≥25/min. HR ≥110/min. PEF 33–50% best or predicted. Speaks in phrases only.

Setting: Emergency department

Life-Threatening

Life-Threatening / Near-Fatal

Silent chest, cyanosis, feeble respiratory effort, confusion, exhaustion, drowsiness. SpO₂ <92%. PEF <33%. PaCO₂ ≥45 mmHg, pH <7.35. Bradycardia or hypotension.

Setting: ICU admission

Emergency Management

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Do not delay treatment. Administer oxygen, bronchodilators, and systemic corticosteroids simultaneously in severe presentations. Continuous monitoring with pulse oximetry is mandatory. Obtain ABG if SpO₂ <92%, features of life-threatening attack, or poor response to initial treatment.

Step 1 — Immediate (within minutes)

Oxygen: Titrate to maintain SpO₂ 94–98%. Avoid hyperoxaemia (routine high-flow O₂ is not recommended unless life-threatening). Use nasal prongs or Hudson mask.
Salbutamol nebulised: 5 mg via oxygen-driven nebuliser, repeated every 20 minutes for 3 doses in the first hour. Can also use 4–8 puffs of salbutamol 100 µg via MDI + spacer (equivalent efficacy in mild–moderate attacks). Continuous nebulisation (10–15 mg/hr) for severe attacks.
Ipratropium bromide: 500 µg nebulised, added to salbutamol every 20 minutes for 3 doses in moderate–severe attacks and life-threatening presentations.
Systemic corticosteroids — within 1 hour:

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Prednisolone

Generic · Oral corticosteroid · First-line for most acute attacks

Adult dose 50 mg PO once daily for 5–7 days (no taper required for courses ≤7 days in patients not on regular OCS)

Paediatric dose 1–2 mg/kg PO once daily (max 50 mg) for 3–5 days

Renal adjustment None required; active metabolite (prednisolone) does not require hepatic conversion

PBS status ✔ PBS General Benefit

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Hydrocortisone

Generic · IV corticosteroid · For severe/life-threatening or vomiting patients

Adult dose 200 mg IV bolus then 100 mg IV every 6–8 hours until able to take oral prednisolone

Paediatric dose 4–8 mg/kg IV (max 200 mg) then 4 mg/kg IV every 6 hours

Renal adjustment None required

PBS status ✔ PBS General Benefit

Step 2 — Escalation (poor response after 1 hour)

IV magnesium sulphate: 2 g (adults) or 25–40 mg/kg (children, max 2 g) IV over 20 minutes. Improves bronchodilation and reduces ICU admission. Monitor for hypotension and flushing. NOT for routine use — reserved for severe/life-threatening attack or PEF <50% predicted after initial treatment.
Continuous nebulised salbutamol: 10–15 mg/hr via oxygen-driven nebuliser for persistent severe obstruction.
Aminophylline: 5 mg/kg IV loading over 20 min (omit if already on theophylline), then 0.5–0.7 mg/kg/hr infusion. Rarely used in Australia due to narrow therapeutic index and lack of strong evidence. Requires theophylline level monitoring.

Step 3 — ICU / Intubation

Ketamine: 1–2 mg/kg IV — useful as an induction agent for intubation in the asthmatic patient due to bronchodilatory properties.
Ventilation strategy: Low tidal volume (6–8 mL/kg), low respiratory rate (10–12/min), long expiratory time (I:E ratio ≥1:3), permissive hypercapnia acceptable. Avoid auto-PEEP.
Indications for intubation: Respiratory arrest, altered consciousness with respiratory failure, severe exhaustion, PaCO₂ rising despite maximal therapy.

ICU Admission Criteria

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Refer immediately to ICU if any of the following are present: Life-threatening features (silent chest, cyanosis, altered consciousness, exhaustion), SpO₂ <92% despite supplemental oxygen, PaCO₂ ≥45 mmHg, deteriorating PEF despite treatment, need for intubation and mechanical ventilation, or no improvement after 1 hour of intensive therapy.

Discharge Planning

Discharge criteria: SpO₂ ≥94% on room air for ≥4 hours, stable for ≥1 hour on 4-hourly salbutamol, PEF ≥75% predicted or personal best, able to tolerate oral medications, and patient education completed.
Prescribe or step-up controller therapy — ensure all patients leave on ICS-containing regimen.
Provide written Asthma Action Plan (AAP) — strongly associated with reduced readmission (NHMRC evidence level I).
Review by GP or respiratory specialist within 1 week of discharge.
Ensure adequate inhaler technique assessment and spacer provision.
Prednisolone course (5–7 days) to complete — ensure prescription is filled before discharge.

Biologics for Severe Asthma

Biologic therapies are indicated for patients with severe uncontrolled asthma despite optimised inhaled therapy (GINA Step 5). In Australia, these are specialist-initiated and require PBS Authority approval. Eligibility criteria vary by agent but generally require evidence of T2-high inflammation and ≥2 exacerbations in the preceding 12 months despite high-dose ICS-LABA (± LAMA) for ≥6 months.

ℹ️

PBS eligibility: All biologics for severe asthma require Authority Required listing on the PBS. Initiation is restricted to respiratory physicians, clinical immunologists/allergists, or paediatric respiratory specialists. Patients must have confirmed asthma diagnosis, T2-high biomarkers (eosinophils, FeNO, or IgE depending on agent), and documented adherence to high-dose ICS-LABA for ≥3–6 months.

Anti-IgE — Omalizumab

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Omalizumab (Xolair®)

Novartis · Anti-IgE monoclonal antibody

Mechanism Binds free IgE, preventing IgE binding to FcεRI on mast cells and basophils, reducing allergic inflammation cascade

Indication Moderate-to-severe persistent allergic asthma with positive SPT/sIgE to perennial aeroallergen, age ≥6 years, uncontrolled on ICS

Adult dose 150–375 mg SC every 2–4 weeks, dose and frequency based on body weight and baseline IgE (see dosing table; total IgE must be 30–1500 IU/mL)

Paediatric dose ≥6 years: same weight/IgE-based dosing table as adults

Key monitoring Assess response at 16 weeks; discontinue if no improvement. Observe for 2 hours after first injection, then 30 min subsequent

PBS status 🔴 PBS Authority Required (Specialist only)

Anti-IL-5 — Mepolizumab & Reslizumab

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Mepolizumab (Nucala®)

GSK · Anti-IL-5 monoclonal antibody

Mechanism Binds IL-5, blocking eosinophil maturation, activation, and survival; reduces blood and sputum eosinophils

Indication Severe eosinophilic asthma with blood eosinophils ≥300 cells/µL (or ≥150 cells/µL with documented eosinophilic exacerbations), ≥2 exacerbations/year despite ICS-LABA

Adult dose 100 mg SC once every 4 weeks

Paediatric dose ≥6 years: 40 mg SC every 4 weeks (weight <40 kg); 100 mg SC every 4 weeks (≥40 kg)

Renal/hepatic No formal dose adjustment; caution in severe hepatic impairment

PBS status 🔴 PBS Authority Required (Specialist only)

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Reslizumab (Cinqaero®)

Teva · Anti-IL-5 monoclonal antibody

Mechanism Humanised anti-IL-5 monoclonal antibody; neutralises circulating IL-5

Indication Severe eosinophilic asthma with blood eosinophils ≥400 cells/µL, uncontrolled on ICS-LABA

Adult dose 3 mg/kg IV infusion over 20–50 minutes every 4 weeks

Renal/hepatic No dose adjustment studied; use with caution

PBS status 🔴 PBS Authority Required (Specialist only)

Anti-IL-5Rα — Benralizumab

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Benralizumab (Fasenra®)

AstraZeneca · Anti-IL-5Rα monoclonal antibody

Mechanism Binds IL-5Rα on eosinophils and basophils; induces near-complete eosinophil depletion via enhanced antibody-dependent cell-mediated cytotoxicity (ADCC)

Indication Severe eosinophilic asthma with blood eosinophils ≥300 cells/µL, uncontrolled on high-dose ICS-LABA

Adult dose 30 mg SC every 4 weeks for 3 doses (loading), then every 8 weeks (maintenance)

Paediatric dose ≥12 years: adult dosing

Renal/hepatic No formal dose adjustment

PBS status 🔴 PBS Authority Required (Specialist only)

Anti-IL-4Rα — Dupilumab

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Dupilumab (Dupixent®)

Sanofi · Anti-IL-4Rα monoclonal antibody

Mechanism Blocks IL-4 and IL-13 signalling by binding IL-4Rα subunit; suppresses T2 inflammation across multiple pathways (eosinophils, IgE, FeNO)

Indication Severe uncontrolled asthma with T2-high biomarkers (blood eosinophils ≥150 cells/µL OR FeNO ≥20 ppb); OCS-dependent asthma; comorbid moderate-severe atopic dermatitis or nasal polyposis

Adult dose 400 mg SC loading (2 × 200 mg injections), then 200 mg SC every 2 weeks. OCS-dependent patients: 600 mg loading (2 × 300 mg), then 300 mg SC every 2 weeks

Paediatric dose ≥12 years (≥30 kg): adult dosing

Renal/hepatic No formal dose adjustment

PBS status 🔴 PBS Authority Required (Specialist only)

Biologic Selection Guide

Agent	Target	Key Biomarker Criteria	Route	Frequency	Key Advantage
Omalizumab	IgE	sIgE+ to perennial allergen, total IgE 30–1500 IU/mL	SC	Every 2–4 weeks	Allergic phenotype with allergen sensitisation
Mepolizumab	IL-5	Blood eosinophils ≥300/µL	SC	Every 4 weeks	Strong evidence in EGPA comorbidity
Reslizumab	IL-5	Blood eosinophils ≥400/µL	IV	Every 4 weeks	Alternative to mepolizumab; IV infusion in clinic
Benralizumab	IL-5Rα	Blood eosinophils ≥300/µL	SC	Every 8 weeks (maintenance)	Complete eosinophil depletion; less frequent dosing
Dupilumab	IL-4Rα	Eosinophils ≥150/µL or FeNO ≥20 ppb	SC	Every 2 weeks	Broadest biomarker eligibility; atopic dermatitis/nasal polyposis comorbidity

⚠️

OCS weaning: Patients on maintenance oral corticosteroids who commence a biologic should be weaned under specialist supervision. Monitor for adrenal insufficiency during OCS withdrawal — morning cortisol levels should be checked. Dose reduction of 2.5–5 mg every 2–4 weeks is standard once biologic response is confirmed.

Special Populations

🏃 Exercise-Induced Bronchoconstriction (EIB)

EIB affects up to 90% of people with poorly controlled asthma and ~10% of the general population, including elite athletes.

Diagnosis: ≥10% fall in FEV₁ after 6–8 minutes of vigorous exercise or eucapnic voluntary hyperventilation (EVH) challenge. A 15% fall is diagnostic.

Pre-exercise management: SABA (salbutamol 200 µg) 10–15 minutes before exercise — provides 2–4 hours of protection. If EIB occurs despite pre-treatment >2 times/week, initiate regular ICS.

Non-pharmacological: 10–15 minute graduated warm-up (can induce a refractory period lasting 2–3 hours), nasal breathing, face covering in cold weather, avoid exercise during high-pollen or high-pollution days.

Refractory EIB despite ICS: Add LTRA (montelukast) — particularly effective for EIB. If inadequate, consider LABA (but never as monotherapy).

Elite athletes: Therapeutic Use Exemption (TUE) required for inhaled β₂ agonists. Salbutamol: up to 1600 µg/24 hr permitted without TUE (WADA 2024); formoterol up to 54 µg/24 hr.

🏭 Occupational Asthma

Occupational asthma accounts for 9–15% of adult-onset asthma in Australia. It is classified as either sensitiser-induced (immunological, with latency period) or irritant-induced (reactive airways dysfunction syndrome — RADS, no latency).

High-risk occupations in Australia: Bakeries (flour dust), isocyanate exposure (spray painting, manufacturing), wood dust (carpentry), healthcare (latex, glutaraldehyde), agriculture (grain dust, pesticides), mining (diesel exhaust, blasting).

Diagnosis: Serial peak flow monitoring (4-hourly for 2–4 weeks at work and away from work); ≥20% work-related variation is significant. Specific inhalation challenge (gold standard, available at specialised centres). sIgE to occupational allergens where applicable.

Management: Complete cessation of exposure is the most effective intervention. Pharmacotherapy as per GINA stepwise approach. Workplace modification (respiratory protection, ventilation) may be sufficient in some cases.

Legal: Occupational asthma is a notifiable workplace illness under WHS legislation in all Australian states/territories. Workers' compensation (WorkCover/Comcare) claims are supported. Employers must provide safe working environments under the Work Health and Safety Act 2011 (Cth).

Prognosis: Early removal from exposure (within 12 months of symptom onset) is associated with better outcomes. Delayed diagnosis leads to persistent asthma in up to 70% of cases even after exposure cessation.

💊 Aspirin-Exacerbated Respiratory Disease (AERD)

AERD (Samter's triad) comprises asthma, NSAID/aspirin sensitivity, and chronic rhinosinusitis with nasal polyposis (CRSwNP). Prevalence is approximately 7% of adult asthmatics but up to 15% of severe asthmatics.

Pathophysiology: Overproduction of cysteinyl leukotrienes (LTC₄, LTD₄, LTE₄) and shunting of arachidonic acid metabolism away from COX-1 pathway after NSAID exposure, leading to mast cell and eosinophil activation.

Clinical features: Respiratory reaction (bronchospasm, rhinorrhoea, periorbital oedema) within 30–120 minutes of ingesting aspirin or any COX-1 inhibiting NSAID. Cross-reactivity with all traditional NSAIDs.

Management: Strict avoidance of aspirin and traditional NSAIDs. Paracetamol is generally tolerated at standard doses (<1000 mg). COX-2 selective inhibitors (celecoxib) may be used with caution under specialist supervision. Dupilumab is particularly effective for AERD given its efficacy across asthma, CRSwNP, and reduction of cysteinyl leukotriene production.

Aspirin desensitisation: Available at specialist centres. Performed under monitored conditions with escalating doses of aspirin, followed by maintenance aspirin 300–600 mg daily. Improves nasal polyposis and reduces asthma exacerbations. Should be considered in patients requiring dual antiplatelet therapy.

🤰 Pregnancy Management

Key principle: Uncontrolled asthma poses a greater risk to the fetus (preterm birth, low birth weight, pre-eclampsia, neonatal hypoxia) than standard controller medications. Treatment should not be stopped or reduced during pregnancy without specialist input.

ICS preference: Budesonide has the most extensive safety data in pregnancy (Category A in Australian categorisation — now superseded by the FDA-style narrative labelling but remains the preferred ICS). Fluticasone propionate is also considered safe. Medium-dose ICS is preferred over high-dose if adequate control is maintained.

LABA: Formoterol and salmeterol have not shown teratogenic effects in registry data. Continue ICS-LABA if previously well controlled on this combination.

Montelukast: Generally avoided in pregnancy due to limited safety data; discontinue unless clearly necessary for severe asthma control.

SABA: Salbutamol is safe and is the reliever of choice during pregnancy.

Acute exacerbations: Treat aggressively. Prednisolone and hydrocortisone are acceptable in pregnancy. Salbutamol nebulisation and oxygen are first-line. Untreated hypoxia is more harmful than medications. Continuous fetal monitoring from viability (≥23 weeks).

Labour and delivery: Continue all controller medications. SABA should be available during labour. Epidural analgesia is preferred (reduces oxygen demand). Caesarean section for obstetric indications only — asthma alone is not an indication.

Breastfeeding: All inhaled medications and prednisolone are compatible with breastfeeding. Biologic safety data in breastfeeding are limited — discuss risk–benefit with specialist.

👴 Elderly / Renal / Hepatic Considerations

Elderly (≥65 years): Higher mortality from asthma in this group. Atypical presentations (exertional dysphea, chronic cough without wheeze) are common — consider ACO with COPD. Use spacers routinely (arthritis may impair MDI coordination). Drug interactions: β-blockers (including eye drops for glaucoma) may worsen bronchospasm. Long-term OCS use increases osteoporosis risk — ensure bisphosphonate prophylaxis and bone density monitoring (DEXA).

Renal impairment: No dose adjustment required for ICS, LABA, LAMA, or most biologics. Aminophylline clearance is reduced — reduce infusion rate and monitor levels. OCS can precipitate fluid retention; use lowest effective dose.

Hepatic impairment: Theophylline/aminophylline clearance is significantly reduced — halve the dose and monitor levels closely. Budesonide (high first-pass metabolism) may have increased systemic bioavailability with severe hepatic impairment. Biologics have no specific hepatic dose adjustments.

🛡️ Immunocompromised Patients

High-dose ICS (≥1000 µg budesonide/day or equivalent) increases the risk of oropharyngeal candidiasis and may contribute to adrenal suppression. Encourage mouth rinsing and spacer use.

Biologic initiation in immunocompromised patients (transplant recipients, biologic for autoimmune disease) requires specialist discussion. Omalizumab, mepolizumab, benralizumab, and dupilumab do not cause generalised immunosuppression, but the impact of combined immunomodulation should be assessed.

OCS use compounds infection risk — prioritise steroid-sparing strategies. Annual influenza and pneumococcal (Prevenar 13 then Pneumovax 23) vaccination recommended for all asthmatics, especially those on OCS or biologics.

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander Health Considerations in Asthma

Asthma has a disproportionate impact on Aboriginal and Torres Strait Islander Australians. Understanding and addressing the social, cultural, and environmental determinants of this inequity is essential for safe, effective, and culturally responsive care.

Prevalence

Aboriginal and Torres Strait Islander Australians experience 1.4–2.1 times the prevalence of asthma compared with non-Indigenous Australians. Prevalence is highest in children aged 0–14 years and in remote communities (AIHW 2023).

Hospitalisation & Mortality

Hospitalisation rates for asthma are 2–3 times higher, and mortality is 2.5 times higher than in non-Indigenous Australians. The gap is widening for adults over 55 years.

Environmental Triggers

Overcrowded housing increases allergen exposure (dust mites, mould). Outdoor dust in remote communities, bushfire smoke exposure, and wood-fire heating all contribute. Air quality monitoring may be unavailable in remote areas.

Access to Diagnosis

Spirometry and FeNO testing are unavailable in many remote Aboriginal Community Controlled Health Organisations (ACCHOs). Training local health workers in peak flow monitoring and symptom assessment tools (e.g., Asthma Control Questionnaire in plain language) is essential. Telehealth respiratory specialist consultations should be facilitated.

Medication Access & Adherence

PBS medications may require transport to distant pharmacies. Inhaler technique education by Aboriginal Health Workers/Practitioners (AHW/Ps) improves outcomes. Shortage of AHW/Ps in remote areas is a significant barrier. Exploring long-acting injectable biologics (8-weekly benralizumab, 4-weekly mepolizumab) may reduce adherence burden where clinic access is intermittent.

Asthma Action Plans

Written Asthma Action Plans should be developed in culturally appropriate plain English, with visual aids and local language translations where available. Shared decision-making with patients and families, and involvement of AHW/Ps, is essential. Asthma Australia provides Indigenous-specific action plan resources.

Smoking & ETS

Tobacco smoking rates among Aboriginal and Torres Strait Islander Australians remain approximately 37% (vs 10% non-Indigenous). Second-hand smoke is a major asthma trigger. Culturally safe smoking cessation programs (e.g., Tackling Indigenous Smoking) should be integrated into asthma management. Offer NRT and refer to Quitline 13 7848 or local cessation support.

Cultural Safety

Recognise the impact of colonisation, intergenerational trauma, and systemic racism on healthcare engagement. Use yarning-based consultations. Ensure gender-sensitive service delivery. Support continuity of care through regular GP visits at ACCHOs. Acknowledge the role of family and community in chronic disease self-management.

📚 References

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3. Australian Institute of Health and Welfare (AIHW). Asthma. Cat. no. ACM 33. Canberra: AIHW; 2023.
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10. Asthma Australia. The Hidden Cost of Asthma. Sydney: Asthma Australia; 2023. Available from: https://www.asthmaaustralia.org.au.
11. Beasley R, Holliday M, Reddel HK, et al. Controlled trial of budesonide-formoterol as needed for mild asthma. N Engl J Med. 2019;380(21):2020–2030. doi:10.1056/NEJMoa1901963.
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13. Australian Indigenous HealthInfoNet. Asthma among Aboriginal and Torres Strait Islander people — Summary. Perth: Edith Cowan University; 2023. Available from: https://healthinfonet.ecu.edu.au.
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15. Reddel HK, Bacharier LB, Bateman ED, et al. Global Initiative for Asthma (GINA) Strategy 2021 — executive summary and rationale for key changes. Eur Respir J. 2022;59(1):2102730. doi:10.1183/13993003.02730-2021.