zafirlukast, Accolate

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GENERIC NAME: zafirlukast

BRAND NAME: Accolate

DRUG CLASS AND MECHANISM: Zafirlukast is an oral leukotriene receptor antagonist used for treating asthma. Leukotrienes are a group of chemicals manufactured in the body from arachidonic acid. Release of leukotrienes within the body, for example, by allergic reactions, promotes inflammation in many diseases such as asthma, a disease in which inflammation occurs in the lungs. Zafirlukast blocks the binding of leukotriene types D4 (LTD4), and E4 (LTE4) and the promotion of inflammation. It was approved by the FDA in September 1996.



PREPARATIONS: Tablets: 10 and 20 mg.

STORAGE: Tablets should be stored at room temperature, between 15 C and 30 C (59 F and 86 F).

PRESCRIBED FOR: Zafirlukast is used for the treatment of chronic asthma. It also is effective in preventing exercise-induced asthma and in relieving the symptoms of allergic rhinitis. For the treatment of asthma, zafirlukast starts working only after 3 to 14 days of therapy. Therefore, it should not be used for treating an acute asthmatic attack because immediate relief is needed.

DOSING: The recommended dose for treating asthma is 10 mg twice daily for children 5-11 years of age and 20 mg twice daily for individual 12 years of age and older. Food reduces the absorption of zafirlukast. Therefore, it should be taken either 1 hour before or 2 hours after meals.

DRUG INTERACTIONS: Zafirlukast inhibits the activity of cytochrome isozymes CYP 3A4 and CYP 2C9. The CYP 3A4 isozyme is responsible for metabolism (elimination) of many drugs. Thus far, data in humans are very limited. In one small study, zafirlukast was shown to interact with warfarin (Coumadin), resulting in increased "thinning" of blood and a decreased ability of blood to clot. This can increase the risk of bleeding.

Until more data are available, zafirlukast should be used very cautiously in patients taking drugs metabolized by CYP3A4 including alprazolam (Xanax), carbamazepine (Tegretol), cyclosporine (Neoral; Sandimmune), dihydropyridine, calcium channel blockers, felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nifedipine (Procardia; Adalat), nimodipine (Nimotop), and amlodipine (Norvasc); diltiazem (Cardizem; Tiazac; Dilacor), erythromycin, lovastatin (Mevacor), quinidine (Quinidex; Quinaglute), simvastatin (Zocor), triazolam (Halcion), verapamil (Calan; Isoptin; Verelan; Covera-HS).

Erythromycin reduces the absorption of zafirlukast, potentially reducing the effect of zafirlukast.

PREGNANCY: Safe use of zafirlukast during pregnancy has not been established. Physicians may prescribe zafirlukast during pregnancy if it is felt that its benefits outweigh the potential unknown risks.

NURSING MOTHERS: Zafirlukast is secreted into breast milk and should not be used by women who breast-feed.

SIDE EFFECTS: The most common side effects of zafirlukast are headache, dizziness, nausea, diarrhea, abdominal pain, sore throat, respiratory infections, and rhinitis. Liver failure has been associated with zafirlukast treatment.

Reference: FDA Prescribing Information

Last Editorial Review: 9/7/2012

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