Zafirlukast is an orally administered leukotriene receptor antagonist (LTRA) used for the chronic treatment of asthma. While zafirlukast is generally well tolerated, headache and stomach upset often occur. Some rare side effects can occur, which can be life-threatening, such as liver failure. Churg-Strauss syndrome has been associated with zafirlukast, but the relationship isnt thought to be causative in nature. Overdoses of zafirlukast tend to be self-limiting. Zafirlukast, like other LTRAs, works by inhibiting the immune system. Through its action on inflammatory cells in the lungs, zafirlukast reduces the production of inflammatory mediators that are implicated in the pathogenesis of asthma. Zafirlukast is extensively hepatically metabolized by an enzyme called CYP2C9. Zafirlukast inhibits the action of CYP3A4, leading to drug-drug interactions with other drugs that are metabolized by CYP3A4. Genetic differences in LTC4 synthase and CYP2C9 may predict how a person reacts to zafirlukast treatment. Zafirlukast (brand name Accolate) was the first cysteinyl leukotriene receptor antagonist approved in the United States. It is now approved in many other countries under other brand names. Medical uses
Zafirlukast is FDA-approved for the prevention and treatment of asthma in adults and children older than 5 years old. Like other leukotriene receptor antagonists, zafirlukast is thought to be useful for the long-term treatment of asthma, but it is generally less effective than inhaled glucocorticoids as monotherapy (which are the standard of care) or long-acting beta-2 agonists in combination therapy. Notably, zafirlukast is ineffective in the event of an acute asthma attack.
It is practically insoluble in water, slightly soluble in methanol, and freely soluble in tetrahydrofuran, dimethylsulfoxide, and acetone. History
Zafirlukast was the first cysteinyl leukotriene receptor antagonist approved in the United States. Zafirlukast was approved in 1996. Society and culture
Economics
While preliminary evidence suggests that zafirlukast may reduce healthcare costs, the cost-effectiveness of using zafirlukast has not been established. Brand names
Research
Mechanism of action
There is some research to suggest that zafirlukast actually acts as a partial inverse agonist at the CysLT1 receptor, though zafirlukast is still classified as an antagonist at this receptor. The possible clinical significance of this effect, if true, is unknown. Other indications
There is some evidence that suggests that zafirlukast may be beneficial in the treatment of chronic urticaria (hives), whether due to a known cause such as cold-exposure or due to an unknown cause (idiopathic). A pilot study indicated that zafirlukast may be of some benefit in cystic fibrosis. In the setting of chronic obstructive pulmonary disorder (COPD), a disease characterized by chronic inflammation of the lungs, zafirlukast has been shown to improve lung function. Veterinary use
Zafirlukast is sometimes used for the treatment of bronchial asthma in cats. References
External links
"Zafirlukast". Drug Information Portal. U.S. National Library of Medicine.