Respiratory Pharmacology

Respiratory diseases fall into two fundamentally different categories:

  • AIRWAY PROBLEM → obstruction & bronchospasm → bronchodilators + inhaled anti-inflammatories
  • PARENCHYMAL PROBLEM → alveolar injury & fibrosis → antifibrotics & immunosuppression

Obstructive Physiology

Airway Disease

  • Problem: Air Cannot Get OUT Of The Lung
  • Usually Reversible

Core Disorders

Bronchodilators

Controllers (Reduce Inflammation)

Severe Asthma Biologics

Symptom Relief

Restrictive Physiology

Parenchymal Disease

  • Problem: Lung Tissue Cannot Expand
  • Usually Progressive

Interstitial Lung Disease

Antifibrotic Therapy

Immune-Mediated Lung Disease Treatment

Key Clinical Distinction

  • Wheezing → bronchodilators
  • Velcro crackles → antifibrotics

They treat completely different diseases.

High-Yield Comparison

Feature Airway Disease Parenchymal Disease
Physiology Obstructive Restrictive
Primary issue Narrow airways Scarred alveoli
Reversibility Often reversible Progressive
Main therapy Bronchodilators ± ICS Antifibrotics / Immunosuppression
Clinical goal Improve airflow Slow decline

How to Think About Dyspnea

  • Wheeze → Airway Drugs
  • Crackles → Fibrosis Drugs
  • Hypoxia Out Of Proportion → ILD Workup