[Leukotrien antagonists in the treatment of allergic rhinitis and comorbidities]

Leukotrienes comprise a family of products of the 5-lipoxigenase pathway of arachidonic acid metabolism. The cysteinil leukotrienes C4, D4 and E4 account for the biologic activity that was previously termed "slow-reacting substance of anaphylaxis". The proinflammatory effects of cysteinil leukotrienes (cys LTs) have been well described in asthma and rhinitis. The cys LTs induce broncospasm (1,000 times more potent than histamine), edema, mucus, hypersecretion, attract inflammatory cells like eosinophils, increase airway hyperreactivity, vascular leakage, and stimulate takikinins. The leukotriene synthesis can be inhibited in two different places; through inhibition of 5 lipooxigenase activating protein (FLAP) in the 5 lipooxigenase pathway, with the drug Zyleuton, or blocking the cysLT1 receptor with the drugs Montelukast, Pranlukast, Zafirlukast. The cysLTs play an important role in pathophysiology of allergic rhinitis and comorbid diseases like rhinosinusitis and nasal polyposis. Antileukotrienes are prescribed in the treatment of allergic rhinitis. Allergic rhinitis is a complex IgE inflammatory disease of the upper airways. It is the most common allergic disease ocurring in 10 to 20% of adults and up to 30% of children. It may be seasonal or perennial, intermittent or persistent. Sneezing, itching, watery rhinorrea and nasal obstruction are classic symptoms. Ocular itching, lacrimation and redness also occur frequently as almost 50% of the patients also have allergic conjunctivitis. Allergic rhinitis may be mild, moderate or severe disease. It may impair cognition, school and work performance. It affects productivity, behavior and mood changes, causes sleep disturbance and diminish the patient's quality of life. Allergic rhinitis is a common comorbid condition with asthma, sinusitis, otitis media, nasal polyposis and recurrent respiratory infections. The purpose of this rewiew article is to know the importante of leukotrienes, its receptors and the clinical efficacy of leukotriene antagonists in allergic rhinitis and comorbid diseases.