COMMON BRAND NAME(S):
Singulair, Montelukast

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Uses: (1) Prevent recurrence of asthmatic episodes; (2) chronically treat asthmatic episodes; (3) zafirlukast is approved to prevent and for long-term treatment of asthma in patients 5 years old or older; (4) montelukast is approved to prevent and treat ongoing asthma in adults and in pediatric patients who are 2 years old or older as well as for use in preventing asthma induced by exercise; (5) montelukast approved for allergic rhinitis.
Author's Note: These medicines are indicated as Step Two medicines (alternatives to low-dose inhaled steroids, cromolyn or nedocromil in mild persistent asthma) in the National Institutes of Health's (NIH, NHLBI) "Guidelines for Diagnosis and Management of Asthma."

Other (unlabeled) generally accepted uses: (1) montelukast and zafirlukast may have a role in preventing spasm of the bronchi caused by exercise; (2) zileuton may have a role in preventing allergic rhinitis or aspirinsensitive asthma; (3) zafirlukast combined with loratadine yielded superb results in treating hay fever symptoms in a study of 458 patients; (4) zafirlukast may help prevent allergic reactions to cats; (5) montelukast could have a role in preventing migraines; (6) montelukast eases delayed pressure urticaria; (7) leukotrienes in general would be expected to have steroid sparing effects in asthma and may have a role in psoriasis.

How These Drugs Work: Zafirlukast and montelukast work by blocking (leukotriene receptor antagonist) action of chemicals called leukotrienes (slow-reacting substances of anaphylaxis). Zileuton works by blocking creation of (leukotriene pathway inhibitor) leukotrienes themselves. By inhibiting action or formation of leukotrienes, all medicines help keep the airvvays open.

Available Dosage Forms and Strengths

Chewable tablets - 4 mg and 5 mg
Tablet - 10 mg

Recommended Dosage Ranges (Actual dosage and schedule must be determined for each patient individually.)

Children 12 to 23 months:
Montelukast only: One 4-mg packet of oral granules or one 4 mg chewable tablet in the evening.
Children 2 to 5:
Montelukast only: One 4-mg chewable tablet in the evening.
Children 5 to 11:
Zafirlukast: 10 mg in the morning and evening.
Children 6 to 14:
Alontelukast only: One 5-mg chewable tablet in the evening.
People 12 to 60 Years or Age:
Zafirlukast: 20 mg twice daily. Zileuton: 600 mg four times a day.
People 15 to 60 years or age:
Montelukast: 10 mg once a day, taken in the evening.
Over 60 Years or Age:
Montelukast: No difference in safety or efficacy, but increased sensitivity to the drug can't yet be ruled out.
Zafirlukast: Maximum blood level can be twice that of younger patients. Prudent to lower doses, but specific guidelines have not been developed. Package insert notes that using typical dose did not result in adverse effects in clinical trials.
Zileuton: Same as those for 12 to 60 years old.

Conditions Requiring Dosing Adjustments

Liver Function:
Montelukast has NOT been studied in liver compromise, but is removed by liver (CYP450 3A4, 2C9 and 2A6) therefore lower doses may be prudent.
Kidnev Function: Dosage changes not needed for the medicines in this class.

Dosing Instructions: Montelukast should be taken in the evening. Zafirlukast should be taken on an empty stomach, 1 hour before or 2 hours after a meal. Zileuton may be given with or without food. It's important to note that these medicines are NOT to be used to stop a sudden (acute) asthma attack, but are usually continued during exacerbation (worsening) of asthma if they have already been started. If you forget a dose: take it right away unless it's nearly time for your next regular dose. If it IS nearly time, just take the scheduled dose. DO NOT double doses.

Usual Duration of Use: Both zafirlukast and zileuton start to work in half an hour. Montelukast peaks and also starts to work in 3-4 hours. It lasts for 24 hours. Zafirlukast significantly relaxes bronchi in 30 minutes, and lasts for 12 hours after a typical dose. Zileuton peaks in 2-4 hours, and with multiple doses may last up to 7 days. Ongoing use requires periodic follow-up with your doctor.

Please Note: The information contained on this page is intended as an educational aid only. It is not intended as medical advice for individual conditions or treatment. It is not a substitute for a medical exam, nor does it replace the need for services provided by medical professionals. Talk to your doctor, nurse or pharmacist before taking any prescription or over the counter drugs or following any treatment or regimen. Only your doctor, nurse or pharmacist can provide you with advice on what is safe and effective for you.

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