Cromolyn and nedocromil belong to a unique group of respiratory drugs called mast cell stabilizers. Unlike bronchodilators or corticosteroids, these drugs work at a very early step in the allergic cascade—they prevent mast cells from releasing inflammatory mediators in the first place.
Although used less frequently today, cromolyn and nedocromil remain important exam topics because they clearly demonstrate:
- Preventive (prophylactic) asthma therapy
- Mast cell–mediated allergic mechanisms
- The difference between prevention and relief drugs
What Are Mast Cell Stabilizers?
Mast cell stabilizers are drugs that prevent the degranulation of mast cells when exposed to allergens or triggers.
Key Concept (Must Remember)
Mast cell stabilizers prevent mediator release but do not reverse existing bronchospasm.
Because of this, they are used prophylactically, not for acute symptom relief.
Common Mast Cell Stabilizers
This article focuses on two classic drugs:
| Drug | Common Brand Names |
|---|---|
| Cromolyn (Cromolyn sodium) | Intal, NasalCrom, Apo-Cromolyn |
| Nedocromil | Tilade |
Pharmacological Classification
Drug Class
- Mast cell stabilizers
- Anti-allergic agents
Therapeutic Category
- Asthma prophylaxis
- Allergic rhinitis prevention
Mechanism of Action (High-Yield Section)
Understanding the mechanism is critical for exams.
How Cromolyn & Nedocromil Work
They:
1. Stabilize mast cell membranes2. Prevent calcium influx into mast cells
3. Inhibit release of:
- Histamine
- Leukotrienes
- Prostaglandins
- Other inflammatory mediators
Net Effect
- Reduced airway inflammation
- Prevention of bronchoconstriction
- Reduced allergic symptoms
Exam Pearl:
These drugs do not have bronchodilator activity.
Individual Drug Profiles
Cromolyn (Cromolyn Sodium)
Drug Class
Mast cell stabilizerKey Features
- Very safe
- Poor systemic absorption
- Requires regular use
Indications
- Prophylaxis of bronchial asthma
- Allergic rhinitis (intranasal form)
- Exercise-induced bronchospasm (prevention)
- Allergic conjunctivitis (ophthalmic form)
Adverse Effects
- Throat irritation
- Cough
- Unpleasant taste
Clinical Pearl
Cromolyn is especially useful in children due to its excellent safety profile.
Nedocromil
Drug Class
Mast cell stabilizerKey Features
- More potent than cromolyn
- Similar preventive role
Indications
- Mild to moderate persistent asthma
- Prevention of allergen-induced bronchospasm
Adverse Effects
- Cough
- Headache
- Bitter taste
Clinical Pearl
Nedocromil has a longer duration and stronger action than cromolyn.
Indications of Mast Cell Stabilizers
Primary Uses
- Mild persistent asthma (prophylaxis)
- Exercise-induced asthma (prevention)
Other Uses
- Allergic rhinitis
- Allergic conjunctivitis
What Mast Cell Stabilizers Do NOT Do (Very Important)
1. ❌ Do not relieve acute asthma attacksThey must be taken regularly before exposure to triggers.
Onset and Duration of Action
| Feature | Cromolyn / Nedocromil |
|---|---|
| Onset | Slow (days to weeks) |
| Role | Preventive |
| Use in acute attack | No |
Adverse Effects and Safety
Common Adverse Effects
- Local throat irritation
- Cough after inhalation
- Bitter or unpleasant taste
Systemic Effects
Minimal to noneKey Advantage:
These drugs have excellent safety profiles and minimal systemic toxicity.
Contraindications & Precautions
- Not effective in acute asthma
- Requires patient compliance
- Should not replace inhaled corticosteroids in moderate–severe asthma
Nursing & Patient Education (High-Yield)
Patient Counseling Points
- Use the medication daily, not as needed
- Start therapy before allergen exposure
- Continue even if asymptomatic
Technique & Compliance
- Proper inhalation technique is essential
- Regular dosing is required for benefit
Comparison with Other Asthma Drugs (Exam-Friendly)
| Feature | Mast Cell Stabilizers | Inhaled Corticosteroids | β₂-Agonists |
|---|---|---|---|
| Role | Preventive | Controller | Reliever |
| Bronchodilation | No | No | Yes |
| Inflammation control | Minimal | Strong | No |
| Acute attack use | No | No | Yes |
Clinical & Exam Pearls (Must Remember)
- Mast cell stabilizers are prophylactic drugs
- Most effective in mild asthma and children
- Must be used before exposure to allergens
- Extremely safe with minimal side effects
- Largely replaced by inhaled corticosteroids in modern practice
Summary Table: Mast Cell Stabilizers at a Glance
| Parameter | Key Point |
|---|---|
| Drug class | Mast cell stabilizers |
| Main drugs | Cromolyn, Nedocromil |
| Role | Asthma prevention |
| Acute relief | ❌ No |
| Safety | Very high |
| Exam relevance | Moderate to high |
FAQs
1. Why are cromolyn and nedocromil not used in acute asthma?
They do not relax bronchial smooth muscle or reverse bronchospasm.
2. How do mast cell stabilizers differ from antihistamines?
They prevent mediator release, whereas antihistamines block histamine action after release.
3. Are mast cell stabilizers steroids?
No, they are non-steroidal anti-allergic drugs.
4. Why must these drugs be used regularly?
Their benefit depends on continuous mast cell stabilization.
5. Can cromolyn be used in children?
Yes, it is very safe and commonly used in pediatric asthma prophylaxis.
6. Which is more potent—cromolyn or nedocromil?
Nedocromil is generally more potent.
7. Do these drugs cause systemic side effects?
No, systemic absorption is minimal.
8. Are mast cell stabilizers still commonly used?
They are less common today but remain important in selected patients and exams.
9. Can they replace inhaled corticosteroids?
No, corticosteroids are more effective for long-term inflammation control.
10. What is the most tested exam concept?
They prevent mast cell degranulation and are used prophylactically.
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- Mast Cell Stabilizers – Cromolyn & Nedocromil
