Respiratory Medicine Classes: An Overview
Respiratory diseases — primarily asthma and COPD — affect over 500 million people globally. Both involve airway obstruction, but through distinct mechanisms: asthma is primarily driven by airway inflammation and hyperresponsiveness (often allergic/eosinophilic), while COPD involves progressive, largely irreversible airflow limitation from smoking-related injury.
Treatment for both relies heavily on inhaled medications — delivering medicine directly to the lung with minimal systemic exposure.
Inhaler Devices: Getting the Fundamentals Right
Before discussing medicines, inhaler technique is paramount — studies show 70-80% of patients use inhalers incorrectly, significantly reducing delivered dose.
Types of inhalers:
- MDI (Metered-Dose Inhaler): Pressurized canister; requires coordination of actuation and inhalation; spacer devices (valved holding chambers) dramatically improve delivery — recommended for all MDI users, essential in children
- DPI (Dry Powder Inhaler): Breath-actuated; no coordination required; requires minimum inspiratory flow rate (~60 L/min); not suitable for severe acute exacerbation (too weak to draw in)
- Soft Mist Inhaler (Respimat): Creates slow-moving aerosol; less coordination required than MDI; longer spray duration
- Nebulizer: Liquid to aerosol via air flow; delivers medicine during normal tidal breathing; useful in severe exacerbation or inability to use handheld devices
Short-Acting Beta-2 Agonists (SABAs): Rescue Inhalers
Mechanism: Bind beta-2 adrenergic receptors on airway smooth muscle → relaxation → bronchodilation within 5-15 minutes; duration 4-6 hours
Medicines:
- Albuterol (salbutamol) (ProAir, Ventolin, Proventil) — most widely used rescue inhaler worldwide
- Levalbuterol (Xopenex) — R-isomer only; less tremor/tachycardia (modest difference); significantly more expensive
Use: PRN for acute symptom relief. High use of rescue inhaler (> 2 days/week) signals inadequately controlled asthma requiring step-up therapy.
Side effects: Tremor, tachycardia, hypokalemia (at high doses), nervousness
Short-Acting Muscarinic Antagonists (SAMAs)
- Ipratropium (Atrovent) — blocks M3 muscarinic receptors in airway → bronchodilation; onset slower than albuterol; preferred in COPD exacerbations; often combined with albuterol in DuoNeb for acute severe COPD
Inhaled Corticosteroids (ICS): Cornerstone of Asthma Control
Mechanism: Reduce eosinophilic airway inflammation; decrease cytokine production, mucus secretion, airway hyperresponsiveness
Medicines:
- Fluticasone propionate (Flovent, ARNUITY) — most widely used; multiple delivery devices; low systemic bioavailability
- Budesonide (Pulmicort) — available as turbuhaler and nebulization; FDA category B in pregnancy (most evidence of safety in pregnancy)
- Beclomethasone (QVAR Redihaler) — smallest particle size; may penetrate small airways better
- Mometasone (Asmanex) — once daily dosing available
- Ciclesonide (Alvesco) — prodrug activated in lung; very low oropharyngeal effects
Key counseling: Rinse mouth after use to prevent oral candidiasis (thrush). High-dose ICS can cause adrenal suppression, bone density loss, growth impairment in children (modest at recommended doses).
Long-Acting Beta-2 Agonists (LABAs)
Mechanism: Same as SABAs but duration 12-24 hours
Medicines:
- Salmeterol (Serevent) — 12-hour; twice daily
- Formoterol (Foradil, Performist) — 12-hour; also fast-acting onset like SABA
- Vilanterol — 24-hour; found only in combination products (Breo Ellipta, Anoro Ellipta)
Critical warning: LABAs must NEVER be used as monotherapy in asthma — associated with increased asthma deaths (SMART trial). Always combine with ICS.
ICS/LABA combination products (backbone of moderate-severe asthma):
- Fluticasone/salmeterol (Advair Diskus, AirDuo)
- Budesonide/formoterol (Symbicort)
- Mometasone/formoterol (Dulera)
- Fluticasone furoate/vilanterol (Breo Ellipta) — once daily
- Fluticasone/umeclidinium/vilanterol (Trelegy Ellipta) — triple therapy for COPD/severe asthma
Long-Acting Muscarinic Antagonists (LAMAs)
First-line bronchodilator in COPD; also used in severe asthma (add-on).
- Tiotropium (Spiriva) — once daily; reduces exacerbations and hospitalizations in COPD; improves lung function
- Umeclidinium (Incruse Ellipta) — once daily
- Glycopyrrolate (Seebri, Lonhala Magnair) — twice daily or once daily
- Aclidinium (Tudorza) — twice daily
Biologic Therapies for Severe Asthma
For patients inadequately controlled on high-dose ICS/LABA, targeted biologics based on inflammatory phenotype:
- Anti-IgE: Omalizumab (Xolair) — binds free IgE; for allergic asthma with IgE > 30 IU/mL; reduces exacerbations ~50%; subcutaneous every 2-4 weeks
- Anti-IL-5: Mepolizumab (Nucala), reslizumab (Cinqair), benralizumab (Fasenra) — for eosinophilic asthma; dramatically reduce exacerbations; mepolizumab also approved for eosinophilic GPA and EGPA
- Anti-IL-4/13: Dupilumab (Dupixent) — for type 2/eosinophilic asthma; also approved for atopic dermatitis, CRS with nasal polyps; subcutaneous every 2 weeks
- Anti-TSLP: Tezepelumab (Tezspire) — broadest efficacy across asthma phenotypes; reduces exacerbations regardless of eosinophil level
Frequently Asked Questions
What is the difference between a controller and rescue inhaler?
Controller inhalers (ICS, ICS/LABA, LAMAs) are taken daily to prevent symptoms and reduce airway inflammation — they do not provide immediate relief. Rescue inhalers (albuterol/SABA) provide rapid bronchodilation for acute symptoms. Using only a rescue inhaler without a controller treats symptoms without addressing underlying inflammation.
Can I use albuterol every day?
Using albuterol more than 2 days per week (or waking up at night due to symptoms more than twice a month) indicates uncontrolled asthma requiring step-up controller therapy. Daily or near-daily rescue inhaler use is NOT appropriate long-term management — it treats symptoms without addressing airway inflammation.
What is MART (Maintenance and Reliever Therapy)?
MART uses a single ICS/formoterol inhaler for both daily maintenance and rescue — exploiting formoterol's fast onset. Current GINA guidelines recommend MART as preferred strategy because it ensures every rescue dose includes an anti-inflammatory dose, preventing the risk of using rescue bronchodilators without ICS coverage.
Do asthma inhalers cause weight gain?
Inhaled corticosteroids at standard doses do not cause systemic side effects including weight gain. Only high-dose ICS or oral corticosteroids (prednisone) cause the typical steroid side effects. This is one reason inhaled delivery is preferred over oral for respiratory inflammation.
Medicines Mentioned in This Article
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult your healthcare provider before making any medication decisions.