Montelukast 10mg for Asthma: Uses, Mechanism, and Dose Chart

What is it?

Montelukast is an oral prescription medicine. It belongs to the class of leukotriene receptor antagonists (LTRAs).

Doctors prescribe it for the long-term management of asthma. It helps prevent asthma attacks during the day and night. It also treats exercise-induced bronchoconstriction (EIB).

Montelukast also relieves symptoms of allergic rhinitis, such as sneezing and a runny nose.

Montelukast is a controller medicine. It is not a rescue drug. It will not stop an acute, sudden asthma attack.

Salt and Composition

Montelukast is formulated as a salt called Montelukast Sodium.

It is available in three common oral formulations:

• 10 mg Film-Coated Tablets: Standard strength for adults and adolescents.
• 5 mg Chewable Tablets: Designed for older children.
• 4 mg Chewable Tablets / Oral Granules: Formulated for younger children and infants.

Common Brand Names

• Singulair
• Montair (Cipla)
• Telekast (Lupin)
• Romilast (Ranbaxy / Sun Pharma)

Dose Chart

Drug / Form	Adult Dose	Child Dose
Montelukast 10 mg Film-Coated Tablet	10 mg once daily at bedtime	Not recommended under 15 years
Montelukast 5 mg Chewable Tablet	Not standard (used only if down-titrated)	5 mg once daily at bedtime (6 to 14 years)
Montelukast 4 mg Chewable Tablet / Granules	Not applicable	4 mg once daily at bedtime (2 to 5 years; granules down to 6 months)

Note: For exercise-induced bronchospasm, take the dose at least 2 hours before exercise.

How it Works in the Human Body

Montelukast acts on the respiratory system. It targets the smooth muscles of the bronchi and the bronchial mucosal lining.

Here is the step-by-step mechanism:

1. Trigger Activation: When an asthma patient inhales an allergen, immune cells like mast cells and eosinophils get activated.
2. Leukotriene Production: These cells convert arachidonic acid into cysteinyl leukotrienes (LTC4, LTD4, and LTE4) via the 5-lipoxygenase pathway.
3. Receptor Binding: Normally, these leukotrienes bind to CysLT1 receptors on bronchial smooth muscles.
4. Airway Reaction: This binding causes severe bronchoconstriction. It also causes mucosal edema, thick mucus secretion, and airway inflammation.
5. Montelukast Blockade: Montelukast is a competitive antagonist. It selectively binds to the CysLT1 receptor and blocks it.
6. Symptom Relief: Because the receptor is blocked, LTD4 cannot bind. Bronchial smooth muscles relax. Swelling decreases, mucus secretion slows down, and breathing becomes easier.

Side Effects

Most patients tolerate Montelukast well. However, side effects can happen.

Common Side Effects

• Headache
• Abdominal pain or stomach upset
• Cough
• Mild fever
• Upper respiratory tract infections

Serious Side Effects (Boxed Warning)

• Neuropsychiatric Events: The FDA issued a boxed warning for Montelukast. It can cause mood changes, vivid dreams, nightmares, agitation, depression, and suicidal thoughts.
• Churg-Strauss Syndrome: In rare cases, patients may develop systemic eosinophilia and vasculitis, especially when tapering systemic oral steroids.
• Hypersensitivity: Skin rash, swelling of the face, and anaphylaxis.

3 Important Exam Points for GPAT

1. Selective CysLT1 Antagonist: Montelukast selectively inhibits the CysLT1 receptor, not the CysLT2 receptor. Do not confuse it with Zileuton, which is a 5-lipoxygenase (5-LOX) enzyme inhibitor.
2. Evening Dosing Rationale: Montelukast is prescribed once daily in the evening. Asthma symptoms and inflammatory leukotriene levels peak naturally in the early morning hours.
3. Metabolism by Cytochrome P450: Montelukast undergoes extensive hepatic metabolism mainly via CYP2C8 and CYP3A4 enzymes. It is excreted almost entirely through bile and feces, not the kidneys.

3 MCQs

Question 1

Montelukast relieves bronchoconstriction by selectively blocking which receptor? A) Beta-2 adrenergic receptor
B) Histamine H1 receptor
C) CysLT1 receptor
D) Muscarinic M3 receptor

Answer: C

Question 2

Which anti-asthma drug acts by inhibiting the 5-lipoxygenase enzyme rather than blocking leukotriene receptors? A) Zafirlukast
B) Zileuton
C) Montelukast
D) Pranlukast

Answer: B

Question 3

Why does the US FDA place a boxed warning on Montelukast? A) Hepatotoxicity
B) Cardiac arrhythmias
C) Neuropsychiatric events
D) Nephrotic syndrome

Answer: C

FAQs

Can Montelukast stop an acute asthma attack?

No. Montelukast has a slow onset of action. It cannot dilate airways rapidly. Always use a fast-acting inhaled beta-2 agonist like Salbutamol for acute attacks.

Why is Montelukast taken at night?

Asthma attacks occur most often in the early morning hours. Taking the tablet at bedtime ensures peak drug levels when the airways are most vulnerable.

Is Montelukast a steroid?

No. Montelukast is a non-steroidal anti-inflammatory drug belonging to the leukotriene receptor antagonist class. It does not carry steroid-related hormonal side effects.