Zafirlukast

Mechanism-of-action classes: Cytochrome P450 2C9 Inhibitors; Leukotriene Receptor Antagonists.

• Zafirlukast is indicated for the prophylaxis and chronic treatment of asthma in adults and children 5 years of age and older.ICD-10: J45.909

• Zafirlukast is contraindicated in patients who are hypersensitive to zafirlukast or any of its inactive ingredients. Zafirlukast is contraindicated in patients with hepatic impairment including hepatic cirrhosis.contraindicated

Because food can reduce the bioavailability of zafirlukast, zafirlukast should be taken at least 1 hour before or 2 hours after meals. Adults and Children 12 years of age and older The recommended dose of zafirlukast in adults and children 12 years and older is 20 mg twice daily. Pediatric Patients 5 through 11 years of age The recommended dose of zafirlukast in children 5 through 11 years of age is 10 mg twice daily. Elderly Patients Based on cross-study comparisons, the clearance of zafirlukast is reduced in elderly patients (65 years of age and older), such that C max and AUC are approximately twice those of younger adults. In clinical trials, a dose of 20 mg twice daily was not associated with an increase in the overall incidence of adverse events or withdrawals because of adverse events in elderly patients. Patients with Hepatic Impairment Zafirlukast is contraindicated in patients with hepatic impairment including hepatic cirrhosis (see Contraindications). The clearance of zafirlukast is reduced in patients with stable alcoholic cirrhosis such that the C max and AUC are approximately 50 to 60% greater than those of normal adults. Zafirlukast has not been evaluated in patients with hepatitis or in long-term studies of patients with cirrhosis. Patients with Renal Impairment Dosage adjustment is not required for patients with renal impairment.

Hepatotoxicity Cases of life-threatening hepatic failure have been reported in patients treated with zafirlukast. Cases of liver injury without other attributable cause have been reported from post-marketing adverse event surveillance of patients who have received the recommended dose of zafirlukast (40 mg/day). In most, but not all post-marketing reports, the patient’s symptoms abated and the liver enzymes returned to normal or near normal after stopping zafirlukast. In rare cases, patients have either presented with fulminant hepatitis or progressed to hepatic failure, liver transplantation and death. In extremely rare post-marketing cases, no clinical symptoms or signs suggestive of liver dysfunction were reported to precede the latter observations. Physicians may consider the value of liver function testing. Periodic serum transaminase testing has not proven to prevent serious injury but it is generally believed that early detection of drug-induced hepatic injury along with immediate withdrawal of the suspect drug enhances the likelihood for recovery. Patients should be advised to be alert for signs and symptoms of liver dysfunction (eg, right upper quadrant abdominal pain, nausea, fatigue, lethargy, pruritus, jaundice, flu-like symptoms, and anorexia) and to contact their physician immediately if they occur. Ongoing clinical assessment of patients should govern physician interventions, including diagnostic evaluations and treatment.

Adults and Children 12 years of age and older The safety database for zafirlukast consists of more than 4,000 healthy volunteers and patients who received zafirlukast, of which 1,723 were asthmatics enrolled in trials of 13 weeks duration or longer. A total of 671 patients received zafirlukast for 1 year or longer. The majority of the patients were 18 years of age or older; however, 222 patients between the age of 12 and 18 years received zafirlukast. A comparison of adverse events reported by ≥1% of zafirlukast-treated patients, and at rates numerically greater than in placebo-treated patients, is shown for all trials in the table below. Adverse Event Zafirlukast N=4,058 PLACEBO N=2,032 Headache 12.9% 11.7% Infection 3.5% 3.4% Nausea 3.1% 2.0% Diarrhea 2.8% 2.1% Pain (generalized) 1.9% 1.7% Asthenia 1.8% 1.6% Abdominal Pain 1.8% 1.1% Accidental Injury 1.6% 1.5% Dizziness 1.6% 1.5% Myalgia 1.6% 1.5% Fever 1.6% 1.1% Back Pain 1.5% 1.2% Vomiting 1.5% 1.1% SGPT Elevation 1.5% 1.1% Dyspepsia 1.3% 1.2% The frequency of less common adverse events was comparable between zafirlukast and placebo. Rarely, elevations of one or more liver enzymes have occurred in patients receiving Zafirlukast in controlled clinical trials. In clinical trials, most of these have been observed at doses four times higher than the recommended dose.

No deaths occurred at oral zafirlukast doses of 2,000 mg/kg in mice (approximately 210 times the maximum recommended daily oral dose in adults and children on a mg/m2 basis), 2,000 mg/kg in rats (approximately 420 times the maximum recommended daily oral dose in adults and children on a mg/m2 basis), and 500 mg/kg in dogs (approximately 350 times the maximum recommended daily oral dose in adults and children on a mg/m2 basis). Overdosage with zafirlukast has been reported in four patients surviving reported doses as high as 200 mg. The predominant symptoms reported following zafirlukast overdose were rash and upset stomach. There were no acute toxic effects in humans that could be consistently ascribed to the administration of zafirlukast. It is reasonable to employ the usual supportive measures in the event of an overdose; eg, remove unabsorbed material from the gastrointestinal tract, employ clinical monitoring, and institute supportive therapy, if required.

• Sep 26, 1996NDANDA020547Strides Pharma Intl
• Nov 18, 2010ANDAANDA090372Dr Reddys Labs Ltd
• Sep 10, 2020ANDAANDA212475Annora Pharma
• Nov 27, 2023ANDAANDA213163Aurobindo Pharma

1. 1Dyspnoea10412%
2. 2Asthma9211%
3. 3Fatigue829.5%
4. 4Drug Ineffective576.6%
5. 5Cough515.9%
6. 6Nausea505.8%
7. 7Wheezing475.4%
8. 8Headache455.2%
9. 9Off Label Use455.2%
10. 10Rash455.2%
11. 11Pruritus445.1%
12. 12Pneumonia435.0%
13. 13Asthenia414.7%
14. 14Dizziness404.6%
15. 15Malaise404.6%

The 6 most recently updated of 6 ClinicalTrials.gov registrations naming Zafirlukast as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Zafirlukast in Treatment of Marker Relapsed Ovarian Cancer
  Completed · Phase 2 · Interventional · 5 enrolled · Beth Israel Deaconess Medical Center
  NCT04339140updated 2025-12-11
• Crossover Study of Zafirlukast in Preventing Allergen-induced Signs and Symptoms in Response to Cat Dander Challenge
  Not yet recruiting · Phase 2 · Interventional · 12 enrolled · Allergy & Asthma Medical Group & Research Center
  NCT06069063updated 2025-09-22
• The Efficacy of Leukotriene Inhibitor in Adult Patients With Moderate SARS-COV-2 Symptoms (COVID19)
  Unknown · Phase 3 · Interventional · 66 enrolled · King Abdullah International Medical Research Center
  NCT04871828updated 2021-05-10
• Breast Capsular Contracture Following Post-Mastectomy Reconstruction in Women Treated With the Leukotriene Inhibitor Zafirlukast: A Phase II Trial
  Terminated · Phase 2 · Interventional · 4 enrolled · University of California, San Francisco
  NCT02950480updated 2019-10-01
• A Study Evaluating the Persistency of Response With or Without Xolair (Omalizumab) After Long-term Therapy
  Completed · Phase 4 · Interventional · 176 enrolled · Genentech, Inc.
  NCT01125748updated 2014-10-15
• Bioequivalence Study of Zafirlukast Tablets 20 mg of Dr. Reddy's Laboratories Limited Under Fasting Condition
  Completed · Phase 1 · Interventional · 44 enrolled · Dr. Reddy's Laboratories Limited
  NCT01283061updated 2011-01-26

Frequently asked questions

How does Zafirlukast work?

Mechanism-of-action classes: Cytochrome P450 2C9 Inhibitors; Leukotriene Receptor Antagonists.

What is Zafirlukast used for?

According to FDA labeling, Zafirlukast carries indications including: Zafirlukast is indicated for the prophylaxis and chronic treatment of asthma in adults and children 5 years of age and older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Zafirlukast?

Zafirlukast is classified as Leukotriene receptor antagonists, Leukotriene Receptor Antagonist, Cytochrome P450 2C9 Inhibitors, Leukotriene Receptor Antagonists, Bronchodilation, Decreased Tracheo-Bronchial Mucosal Edema.

What are the brand names for Zafirlukast?

Zafirlukast is marketed under brand names including Accolate.

What are the contraindications for Zafirlukast?

Zafirlukast labeling lists contraindications including: Zafirlukast is contraindicated in patients who are hypersensitive to zafirlukast or any of its inactive ingredients. Zafirlukast is contraindicated in patients with hepatic impairment including hepatic cirrhosis.. Always consult the full prescribing information and a clinician.