Leukotrienes are a group of chemicals released from mast cells, which, like histamine, promote inflammation. There are currently 3 anti-leukotrine medications on the market Singulair (Montelukast), Accolate (Zafirlukast) and Zyflo (Zileuton).

The precise role of these medications in asthma is still being decided. Some asthmatics respond well to these drugs, while other asthmatics gain little benefit. They seem to be particularly effective in those people who have asthma attacks triggered by aspirin or exercise. However, inhaled steroids have greater anti-inflammatory effects than anti-leukotrines.

1. Allowing the dose of corticosteroids to be reduced in moderate asthma
2. Helping stabilise people with severe asthma
3. mild asthma as an alternative to low doses of inhaled corticosteroids

 
They are oral medications taken once or twice a day
 
They treat asthma via a completely different way to other available medications.

They are preventive medications and should not be used to relieve an asthma attack.

However, further long term studies are needed to establish the role of anti-leukotriene medications in asthma treatment guideline in particular, whether they should be used as an alternative to low dose inhaled corticosteroid as a first line treatment in patients with mild to moderate persistent asthma.

Dosage and Administration:
Tablet, 10 mg and 5 mg (paediatric, chewable):

Adults over 15 years: 10 mg taken once a day in the evening
Children 6–14 years: 5 mg chewable tablet taken once a day in the evening

Montelukast may be taken with or without food.
 
 
Zafirlukast
Zafirlukast is indicated for the prophylaxis and treatment of asthma in adults and in children aged 12 years and over.

Dosage and Administration:
Tablet, 20 mg and 40 mg

Adults and children 12 years and over: 20–40 mg twice daily. Therapy should be initiated at 20 mg twice daily, which is the usual maintenance dose. Increasing the dosage to 40 mg twice daily may provide additional benefit. Take one hour before meals or two hours after meals.

Dosage and Administration:
Tablet 600 mg

Adults and children 12 years of age and older: 600 milligrams (mg) four times a day.

Because anti-leukotrienes are taken in tablet form, the dosage is easy to monitor.

Zafirlukast should not be taken by people who also take the blood-thinning drug, Warfarin. There is a possible link with both Zafirlukast and Singulair with a rare disorder of blood vessels called Churg-Strauss syndrome, which has appeared in some people when their oral steroids are reduced.

The problem could become serious when changing medications. At some point, doctors, wanting to avoid the adverse side effects of prolonged steroid use, usually replace steroids with leukotriene antagonists. But, when patients respond well to leukotriene antagonists and their doctors take them off the steroids, the change unmasks a systemic inflammation of the blood vessels (vasculitis). This, in turn, could possibly even accelerate the syndrome into its dangerous phase, which can lead to death. Common symptoms include a combination of a flu-like illness, rash, pins and needles or numbness of arms and legs and severe sinusitis.

Zileuton enhances the absorption of theophylline so if you take both of these drugs together then the monitoring of theophylline levels is more critical than usual. Some 4% of the people who have taken Zileuton have shown abnormal liver function and it is recommended that the liver be checked at least every two months for the first year of taking the drug.