Zafirlukast; Uses, Dosage, Side Effects, Drug Interactions

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 6 min read
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Zafirlukast is a tolyl compound and leukotriene receptor antagonist (LTRA), with anti-asthmatic and potential capsular contracture-preventing activities. Upon administration, zafirlukast selectively and competitively binds to and blocks the cysteinyl leukotriene 1 receptor (CYSLTR1), thereby preventing the potent pro-inflammatory mediator's leukotriene C4, D4, and E4 from binding. This prevents leukotriene-mediated actions, including...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

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Article Summary

Zafirlukast is a tolyl compound and leukotriene receptor antagonist (LTRA), with anti-asthmatic and potential capsular contracture-preventing activities. Upon administration, zafirlukast selectively and competitively binds to and blocks the cysteinyl leukotriene 1 receptor (CYSLTR1), thereby preventing the potent pro-inflammatory mediator's leukotriene C4, D4, and E4 from binding. This prevents leukotriene-mediated actions, including enhanced migration of eosinophils and neutrophils, increased adhesion of leukocytes, increased monocyte and neutrophil aggregation, increased airway edema, inflammation, capillary...

Key Takeaways

  • This article explains Mechanism of Action of zafirlukast in simple medical language.
  • This article explains Indications of zafirlukast in simple medical language.
  • This article explains Contra-Indications of zafirlukast in simple medical language.
  • This article explains Dosages of zafirlukast in simple medical language.
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Zafirlukast is a tolyl compound and leukotriene receptor antagonist (LTRA), with anti-asthmatic and potential capsular contracture-preventing activities. Upon administration, zafirlukast selectively and competitively binds to and blocks the cysteinyl leukotriene 1 receptor (CYSLTR1), thereby preventing the potent pro-inflammatory mediator’s leukotriene C4, D4, and E4 from binding. This prevents leukotriene-mediated actions, including enhanced migration of eosinophils and neutrophils, increased adhesion of leukocytes, increased monocyte and bacterial infection. সহজ বাংলা: ব্যাকটেরিয়ার বিরুদ্ধে লড়াই করা শ্বেত রক্তকণিকা।" data-rx-term="neutrophil" data-rx-definition="Neutrophil is a white blood cell important for fighting bacterial infection. সহজ বাংলা: ব্যাকটেরিয়ার বিরুদ্ধে লড়াই করা শ্বেত রক্তকণিকা।">neutrophil aggregation, increased airway edema, pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">inflammation, capillary permeability, and bronchoconstriction. In addition, zafirlukast may decrease collagen deposition, chronic injury or inflammation. সহজ বাংলা: অতিরিক্ত দাগের মতো টিস্যু তৈরি হওয়া।" data-rx-term="fibrosis" data-rx-definition="Fibrosis means excess scar-like tissue formation after chronic injury or inflammation. সহজ বাংলা: অতিরিক্ত দাগের মতো টিস্যু তৈরি হওয়া।">fibrosis, and capsular thickness after implantation, thereby preventing scar tissue.

Zafirlukast is an orally administered leukotriene receptor antagonist (LTRA) used for the chronic treatment of asthma. While zafirlukast is generally well-tolerated, pain in the head or upper neck. সহজ বাংলা: মাথাব্যথা।" data-rx-term="headache" data-rx-definition="Headache means pain in the head or upper neck. সহজ বাংলা: মাথাব্যথা।">headache and stomach upset often occur. Zafirlukast is an oral leukotriene receptor antagonist (LTRA) for the maintenance treatment of asthma, often used in conjunction with an inhaled steroid and/or long-acting bronchodilator. It is available as a tablet and is usually dosed twice daily. Another leukotriene receptor antagonist is montelukast (Singulair), which is usually taken just once daily.

Mechanism of Action of zafirlukast

Zafirlukast is a selective and competitive receptor antagonist of leukotriene D4 and E4 (LTD4 and LTE4), components of slow-reacting substance of anaphylaxis (SRSA). Cysteinyl leukotriene production and receptor occupation have been correlated with the pathophysiology of asthma, including airway edema, smooth muscle constriction, and altered cellular activity associated with the inflammatory process, which contribute to the signs and symptoms of asthma. Patients with asthma were found in one study to be 25-100 times more sensitive to the bronchoconstricting activity of inhaled LTD4 than nonasthmatic subjects. In vitro studies demonstrated that zafirlukast antagonized the contractile activity of three leukotrienes (LTC4, LTD4, and LTE4) in conducting airway smooth muscle from laboratory animals and humans. Zafirlukast prevented intradermal LTD4-induced increases in cutaneous vascular permeability and inhibited the inhaled LTD4-induced influx of eosinophils into animal lungs.

Indications of zafirlukast

Contra-Indications of zafirlukast

Dosages of zafirlukast

  • Strengths: 10 mg; 20 mg

Asthma

  • 20 mg orally twice a day, 1 hour before or 2 hours after meals

Pediatric Asthma

Less than 5 years

  • The safety and effectiveness has not been established.

5 to 11 years

  • 10 mg orally twice a day, 1 hour before or 2 hours after meals

12 years or older

  • 20 mg orally twice a day, 1 hour before or 2 hours after meals

Maximum dosage

Adults
  • 40 mg/day PO.
Elderly
  • 40 mg/day PO.
Adolescents
  • 40 mg/day PO.
Children
  • 5—11 years: 20 mg/day PO.
  • < 5 years: Safety and efficacy have not been established.
Infants
  • Safety and efficacy have not been established.

Side Effects of zafirlukast

The most common

Common

Rare

Drug Interactions of zafirlukast

Zafirlukast may interact with following drugs, supplements & may change the efficacy of drugs

Pregnancy & Lactation of zafirlukast 

FDA pregnancy category B

Pregnancy

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

Zafirlukast passes into breast milk. If you are a breastfeeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding.

References

 

Zafirlukast; Uses, Dosage, Side Effects, Drug Interactions

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Tests to discuss with doctor
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Questions to ask
  • What is the most likely cause of my symptoms?
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Care roadmap for: Zafirlukast; Uses, Dosage, Side Effects, Drug Interactions

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

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Frequently Asked Questions

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When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

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