Leukotriene Receptor Antagonist

Aka: Leukotriene Receptor Antagonist, Leukotriene Synthesis Inhibitor, Accolate, Zafirlukast, Montelukast, Singulair, Zileuton, Zyflo

1. Preparations
   1. Zafirlukast (Accolate)
   2. Montelukast (Singulair)
   3. Zileuton (Zyflo)
2. Mechanism
   1. Attenuates bronchoconstriction and inflammation
   2. Leukotriene Receptor Antagonists
      1. Zafirlukast (Accolate)
      2. Montelukast (Singulair)
   3. Leukotriene Synthesis Inhibitor
      1. Zileuton (Zyflo)
3. Indication: Adjunctive in Asthma and Allergic Rhinitis
   1. Moderate Persistent Asthma
   2. Severe Persistent Asthma
   3. Moderate Chronic Obstructive Pulmonary Disease
   4. Aspirin-induced Asthma
   5. Exercise-Induced Bronchospasm
   6. Allergic Rhinitis
4. Dosing: Zafirlukast (Accolate)
   1. Leukotriene Receptor Antagonist
   2. Avoid at mealtime
      1. Take 1 hour before or 2 hours after meals
   3. Dose
      1. Age >11 years old: 20 mg PO bid
      2. Child 7-11 years old: 10 mg PO bid
5. Dosing: Montelukast (Singulair)
   1. Leukotriene Receptor Antagonist
   2. Dose
      1. Adults: 10 mg PO qhs
      2. Child age 6 to 14 years: 5 mg PO qhs
      3. Child age 2-5 years: 4 mg PO qhs
6. Dosing: Zileuton (Zyflo)
   1. Leukotriene Synthesis Inhibitor
   2. Indicated in age only 12 and over
   3. Dose: 600 mg orally four times daily
   4. Hepatotoxicity in 5% (Monitor liver enzymes q3 months)
   5. Drug interactions: Warfarin, theophylline, Propranolol
   6. Expensive ($273 per month)
7. Efficacy
   1. Modestly effective for maintenance management
   2. Inhaled Steroids are preferred over leukotriene agents
   3. Used as adjunctive therapy in Asthma
   4. Benefit may be limited to patients with the 5-LO and LTC4 polymorphisms
      1. Sampson (2004) RT J Respir Care Practitioners 17:30-2
      2. Wechsler (2005) Am J Respir Crit Care Med 172(1): 12-8
8. Adverse Effects
   1. Multiple P450 drug interactions
      1. Potentiates Warfarin
      2. Potentiates Theophylline
      3. Potentiates Propranolol
   2. Some association with Churg-Strauss Syndrome
      1. Systemic Eosinophilic Vasculitis
      2. Vasculitic rash
      3. Pulmonary and cardiac conditions
   3. Hepatotoxicity with Zileuton (Zyflo)
9. Cost
   1. Among most expensive agents in Asthma
   2. Accolate and Singulair: $90-100 per month
   3. Zyflo: $270 per month
10. References
    1. (1996) Med Lett Drugs Ther 38:111-2
    2. (2000) Med Lett Drugs Ther 42:22-3
    3. Scow (2007) Am Fam Physician 75:65-70
    4. Wilson (2001) Chest 119:2021-6