Montelukast

12.1 Mechanism of Action The cysteinyl leukotrienes (LTC 4 , LTD 4 , LTE 4 ) are products of arachidonic acid metabolism and are released from various cells, including mast cells and eosinophils. These eicosanoids bind to cysteinyl leukotriene (CysLT) receptors. The CysLT type-1 (CysLT 1 ) receptor is found in the human airway (including airway smooth muscle cells and airway macrophages) and on other pro-inflammatory cells (including eosinophils and certain myeloid stem cells). CysLTs have been correlated with the pathophysiology of asthma and allergic rhinitis. In asthma, leukotriene-mediated effects include airway edema, smooth muscle contraction, and altered cellular activity associated with the inflammatory process. In allergic rhinitis, CysLTs are released from the nasal mucosa after allergen exposure during both early-and late-phase reactions and are associated with symptoms of allergic rhinitis. Montelukast is an orally active compound that binds with high affinity and selectivity to the CysLT 1 receptor (in preference to other pharmacologically important airway receptors, such as the prostanoid, cholinergic, or β-adrenergic receptor). Montelukast inhibits physiologic actions of LTD 4 at the CysLT 1 receptor without any agonist activity.

1. INDICATIONS AND USAGE Montelukast sodium tablets are a leukotriene receptor antagonist indicated for: • Prophylaxis and chronic treatment of asthma in patients 2 years of age and older (1.1). • Acute prevention of exercise-induced bronchoconstriction (EIB) in patients 15 years of age and older (1.2). • Relief of symptoms of allergic rhinitis (AR): seasonal allergic rhinitis (SAR) in patients 2 years of age and older , and perennial allergic rhinitis (PAR) in patients 2 years of age and older (1.3). 1.1 Asthma Montelukast sodium is indicated for the prophylaxis and chronic treatment of asthma in adults and pediatric patients 2 years of age and older. 1.2 Exercise-Induced Bronchoconstriction Montelukast sodium is indicated for prevention of exercise-induced bronchoconstriction (EIB) in patients 15 years of age and older. Pediatric use information for patients ages 6 to 14 years of age for acute prevention of exercise-induced bronchoconstriction (EIB) is approved for Merck Sharp & Dohme Corp's montelukast tablet products. However , due to Merck Sharp & Dohme Corp's marketing exclusivity rights , this drug product is not labeled with that pediatric information. 1.3 Allergic Rhinitis Montelukast sodium is indicated for the relief of symptoms of seasonal allergic rhinitis in patients 2 years of age and older and perennial allergic rhinitis in patients 2 years of age and older.

2. DOSAGE AND ADMINISTRATION Administration (by indications): • Asthma (2.1):Once daily in the evening for patients 2 years and older. • Acute prevention of EIB (2.2): One tablet at least 2 hours before exercise for patients 15 years of age and older. • Seasonal allergic rhinitis (2.3): Once daily for patients 2 years and older. • Perennial allergic rhinitis (2.3): Once daily for patients 2 years and older. Dosage (by age): • 15 years and older: one 10-mg tablet. • 2 to 5 years: one 4-mg chewable tablet . • 6 to 14 years: one 5-mg chewable tablet. Patients with both asthma and allergic rhinitis should take only one dose daily in the evening (2.4). 2.1 Asthma Montelukast sodium should be taken once daily in the evening. The following doses are recommended: For adults and adolescents 15 years of age and older: one 10-mg tablet. For pediatric patients 6 to 14 years of age: one 5-mg chewable tablet. For pediatric patients 2 to 5 years of age: one 4-mg chewable tablet. Safety and effectiveness in pediatric patients less than 2 years of age with asthma have not been established. There have been no clinical trials in patients with asthma to evaluate the relative efficacy of morning versus evening dosing. The pharmacokinetics of montelukast are similar whether dosed in the morning or evening. Efficacy has been demonstrated for asthma when montelukast was administered in the evening without regard to time of food ingestion. 2.2 Exercise-Induced Bronchoconstriction (EIB) in Patients 15 Years of Age and Older For prevention of EIB, a single 10 mg dose of montelukast should be taken at least 2 hours before exercise. An additional dose of montelukast should not be taken within 24 hours of a previous dose. Patients already taking montelukast sodium daily for another indication (including chronic asthma) should not take an additional dose to prevent EIB. All patients should have available for rescue a short-acting β‑agonist. Safety and effectiveness in patients younger than 15 years of age have not been established. Daily administration of montelukast sodium for the chronic treatment of asthma has not been established to prevent acute episodes of EIB. Pediatric use information for patients ages 6 to 14 years of age for acute prevention of exercise-induced bronchoconstriction (EIB) is approved for Merck Sharp & Dohme Corp's montelukast tablet products. However , due to Merck Sharp & Dohme Corp's marketing exclusivity rights , this drug product is not labeled with that pediatric information. 2.3 Allergic Rhinitis For allergic rhinitis, montelukast sodium should be taken once daily. Efficacy was demonstrated for seasonal allergic rhinitis when montelukast was administered in the morning or the evening without regard to time of food ingestion. The time of administration may be individualized to suit patient needs. The following doses for the treatment of symptoms of seasonal allergic rhinitis are recommended: For adults and adolescents 15 years of age and older: one 10-mg tablet. For pediatric patients 6 to 14 years of age: one 5-mg chewable tablet. For pediatric patients 2 to 5 years of age: one 4-mg chewable tablet . Safety and effectiveness in pediatric patients younger than 2 years of age with seasonal allergic rhinitis have not been established. The following doses for the treatment of symptoms of perennial allergic rhinitis are recommended: For adults and adolescents 15 years of age and older: one 10-mg tablet. For pediatric patients 6 to 14 years of age: one 5-mg chewable tablet. For pediatric patients 2 to 5 years of age: one 4-mg chewable tablet. Safety and effectiveness in pediatric patients younger than 2 years of age with perennial allergic rhinitis have not been established. 2.4 Asthma and Allergic Rhinitis Patients with both asthma and allergic rhinitis should take only one montelukast sodium dose daily in the evening.

6. ADVERSE REACTIONS Most common adverse reactions (incidence ≥5% and greater than placebo listed in descending order of frequency): upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, diarrhea, otitis media, influenza, rhinorrhea, sinusitis, otitis (6.1). To report SUSPECTED ADVERSE REACTIONS, contact Torrent Pharma Inc. at 1-269-544-2299 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Pediatric use information for patients ages 6 to 14 years of age for acute prevention of exercise-induced bronchoconstriction (EIB) is approved for Merck Sharp & Dohme Corp's montelukast tablet products. However, due to Merck Sharp & Dohme Corp's marketing exclusivity rights, this drug product is not labeled with that pediatric information. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. In the following description of clinical trials experience, adverse reactions are listed regardless of causality assessment. The most common adverse reactions (incidence ≥5% and greater than placebo; listed in descending order of frequency) in controlled clinical trials were: upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, diarrhea, otitis media, influenza, rhinorrhea, sinusitis, otitis. Adults and Adolescents 15 Years of Age and Older with Asthma Montelukast sodium has been evaluated for safety in approximately 2950 adult and adolescent patients 15 years of age and older in clinical trials. In placebo-controlled clinical trials, the following adverse experiences reported with montelukast sodium occurred in greater than or equal to 1% of patients and at an incidence greater than that in patients treated with placebo: Table 1: Adverse Experiences Occurring in ≥1% of Patients with an Incidence Greater than that in Patients Treated with Placebo * Number of patients tested (montelukast sodium and placebo, respectively): ALT and AST, 1935, 1170; pyuria, 1924, 1159. Montelukast 10 mg/day (%) (n=1955) Placebo (%) (n=1180) Body As A Whole Pain, abdominal 2.9 2.5 Asthenia/fatigue 1.8 1.2 Fever 1.5 0.9 Trauma 1.0 0.8 Digestive System Disorders Dyspepsia 2.1 1.1 Pain, dental 1.7 1.0 Gastroenteritis, infectious 1.5 0.5 Nervous System/Psychiatric Headache 18.4 18.1 Dizziness 1.9 1.4 Respiratory System Disorders Influenza 4.2 3.9 Cough 2.7 2.4 Congestion, nasal 1.6 1.3 Skin/Skin Appendages Disorder Rash 1.6 1.2 Laboratory Adverse Experiences* ALT increased 2.1 2.0 AST increased 1.6 1.2 Pyuria 1.0 0.9 The frequency of less common adverse events was comparable between montelukast sodium and placebo. The safety profile of montelukast sodium, when administered as a single dose for prevention of EIB in adult and adolescent patients 15 years of age and older, was consistent with the safety profile previously described for montelukast sodium. Cumulatively, 569 patients were treated with montelukast sodium for at least 6 months, 480 for one year, and 49 for two years in clinical trials. With prolonged treatment, the adverse experience profile did not significantly change. Pediatric Patients 6 to 14 Years of Age with Asthma Montelukast sodium has been evaluated for safety in 476 pediatric patients 6 to 14 years of age. Cumulatively, 289 pediatric patients were treated with montelukast sodium or at least 6 months, and 241 for one year or longer in clinical trials. The safety profile of montelukast sodium in the 8-week, double-blind, pediatric efficacy trial was generally similar to the adult safety profile. In pediatric patients 6 to 14 years of age receiving montelukast sodium, the following events occurred with a frequency ≥2% and more frequently than in pediatric patients who received placebo: pharyngitis, influenza, fever, sinusitis, nausea, diarrhea, dyspepsia, otitis, viral infection, and laryngitis. The frequency of less common adverse events was comparable between montelukast sodium and placebo. With prolonged treatment, the adverse experience profile did not significantly change. Pediatric use information for patients ages 6 to 14 years of age for acute prevention of exercise-induced bronchoconstriction (EIB) is approved for Merck Sharp & Dohme Corp's montelukast tablet products. However , due to Merck Sharp & Dohme Corp's marketing exclusivity rights , this drug product is not labeled with that pediatric information. In studies evaluating growth rate, the safety profile in these pediatric patients was consistent with the safety profile previously described for montelukast sodium. In a 56-week, double-blind study evaluating growth rate in pediatric patients 6 to 8 years of age receiving montelukast sodium, the following events not previously observed with the use of montelukast sodium in this age group occurred with a frequency ≥2% and more

7. DRUG INTERACTIONS No dose adjustment is needed when montelukast sodium is co-administered with theophylline, prednisone, prednisolone, oral contraceptives, terfenadine, digoxin, warfarin, gemfibrozil, itraconazole, thyroid hormones, sedative hypnotics, non-steroidal anti-inflammatory agents, benzodiazepines, decongestants, and Cytochrome P450 (CYP) enzyme inducers [see Clinical Pharmacology (12.3)] .