Montelukast

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Contents 1 Introduction 2 Indications 3 Dosage 4 Pharmacokinetics 5 Adverse-effects 6 Drug-interactions 7 Mechanism-of-action 8 More General Terms 9 Additional Terms 10 Internet Database 11 References

Introduction

• Tradename: Singulair. Generic August 2012 [10]

Indications

• prophylaxis & chronic treatment of asthma in adults & children over 2 years of age

• adjunctive therapy for patients with asthma inadequately controlled on inhaled steroids [5]
• exercise-induced asthma [7]

• seasonal allergic rhinitis in adults & children over 2 years of age [4]

Dosage

• adults: 10 mg PO QD

• 2 hours prior to exercise [7]

• children age 2-5: 4 mg QD [3]

• Tabs: 4, 5 & 10 mg chewable tablets.

Pharmacokinetics

• metabolized in liver by cyt P450 2C9 & 3A4
  

• elimination via liver
• 1/2life = 2.7-5.5 hours

Adverse-effects

• uncommon (< 2%)

• asthenia, fatigue, dyspepsia, rash, fever, hypersensitivity

• rare

• systemic eosinophilia
• Churg-Strauss syndrome

• other

• agitation, aggression, anxiousness, abnormal dreams, hallucinations, depression, insomnia, irritability, restlessness, tremor [9]
• possible association between the use of Singulair & behavior/ mood changes, suicidality ( suicidal thinking & behavior) & suicide [8,9]

• Toxicity:

• no mortality in single doses of 5000 mg/kg in mice & rats.
  
• drug adverse effects of leukotriene receptor antagonists

Drug-interactions

• phenobarbital (no dose adjustment recommended)
• any drug which inhibits cyt P450 2C9 or 3A4 can increase montelukast levels
• any drug which induces cyt P450 2C9 or 3A4 can diminish montelukast levels

Mechanism-of-action

• leukotriene D4 receptor inhibitor

More General Terms

• leukotriene receptor antagonist
• antiasthmatic agent

Additional Terms

• allergic angiitis & granulomatosis of Churg-Strauss
• cysteinyl leukotriene receptor (LTC4 receptor, LTD4 receptor)
• cytochrome P450 2C9; cytochrome P450 BP-1; cytochrome P450 MP-4; S-mephenytoin-4-hydroxylase; limonene 6-monooxygenase; limonene 7-monooxygenase (CYP2C9, CYP2C10)
• cytochrome P450 3A4 (cytochrome P450 C3, nifedipine oxidase, P450-PCN1, NF-25, CYP3A4)

Internet Database

PubChem: 5311297
PubChem: 5284590
PubChem: 60950
PubChem: 60951
PubChem: 4248
PubChem: 5281040
PubChem: 5281041

References

1. Merck & Company
2. Prescriber's Letter 13(3): 2006 Cytochrome P450 drug interactions Detail-Document#: [1] (subscription needed) [2]
3. Journal Watch 21(19):154, 2001 Knorr et al, Pediatrics 108:e48, 2001
4. Singulair (Montelukast) for Seasonal Allergic Rhinitis Prescriber's Letter 10(2):9 2003 Detail-Document#: [3] (subscription needed) [4]
5. Journal Watch 23(24):192, 2003 Bjermer L et al, BMJ 327:891, 2003 <PubMed> PMID: [5] <Internet> [6]
6. Department of Veterans Affairs, VA National Formulary
   - non formulary drug request
7. Prescriber's Letter 14(7): 2007 Montelukast (Singulair) for Exercise-induced Bronchospasm Detail-Document#: [7] (subscription needed) [8]
8. FDA MedWatch [9]
   - Prescriber's Letter 15(5): 2008 Singulair (Montelukast) and Suicide Detail-Document#: [10] (subscription needed) [11]
9. FDA Safety Alert 6/12/2009 Updated Information on Leukotriene Inhibitors: Montelukast (marketed as Singulair), Zafirlukast (marketed as Accolate), and Zileuton (marketed as Zyflo and Zyflo CR) [12]
10. Prescriber's Letter 19(4): 2012 CHART: Anticipated Availability of First-Time Generics Detail-Document#: [13] (subscription needed) [14]

montelukast (Singulair)