## Mechanism and Role of ICS in Asthma **Key Point:** Inhaled corticosteroids (ICS) are the gold standard anti-inflammatory therapy for persistent asthma, but they are NOT rapid-acting agents and should never be used as monotherapy for acute symptom relief. ### Correct Statements About ICS | Feature | Evidence | |---------|----------| | Anti-inflammatory action | Reduce eosinophils, mast cells, T-lymphocytes in airways | | Airway remodelling | Prevent collagen deposition and smooth muscle hypertrophy | | Hyperresponsiveness | Reduce BHR (bronchial hyperresponsiveness) over weeks–months | | Exacerbation prevention | Reduce frequency and severity of attacks by 50–60% | | Onset of action | 4–12 hours; maximal effect at 2–4 weeks | | Acute relief | **NOT suitable** — use SABA (salbutamol) instead | **High-Yield:** ICS work by suppressing the inflammatory cascade (IL-4, IL-5, TNF-α) and reducing mucus production, but this takes time. They are **preventive**, not **rescue** agents. ### Why Option 3 Is Wrong ICS onset is measured in **hours to days**, not minutes. Rapid relief (5–10 min) is the hallmark of **short-acting beta-2 agonists (SABA)** like salbutamol. Confusing ICS with SABA is a common trap in asthma management. **Clinical Pearl:** A patient using ICS for acute wheezing will have a delayed or absent response. This is why ICS + LABA (long-acting beta-agonist) combinations are paired with a separate SABA rescue inhaler. ### Treatment Algorithm ```mermaid flowchart TD A[Asthma diagnosis]:::outcome --> B{Frequency of symptoms?}:::decision B -->|Intermittent| C[SABA as needed]:::action B -->|Persistent| D[Start ICS]:::action D --> E{Controlled on ICS monotherapy?}:::decision E -->|Yes| F[Continue ICS]:::action E -->|No| G[Add LABA to ICS]:::action H[Acute exacerbation]:::urgent --> I[SABA + systemic corticosteroid]:::action ``` **Mnemonic:** **SABA = SAve (rescue)**, **ICS = Inflammatory Control (preventive)**
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