Zafirlukast, as a kind of polypeptide LTC4, LTD4 and LTE4 allergic reactions such as slow reaction substance leukotriene receptor antagonist, competitive inhibition activity of leukotriene, effectively prevent leukotriene polypeptide of the increase in vascular permeability caused by airway edema, and inhibition of leukotriene polypeptide produced by airway eosinophilia cell infiltration, reduce tracheal contraction and inflammation, relieve asthma symptoms. Drugs are highly selective and only ACTS on leukotriene receptor, does not affect the prostaglandins, thromboxane, cholinergic and histamine receptor. Good oral absorption, after about 3 h peak plasma concentration. Medication within 2 h, drug plasma concentration has yet to reach the peak can be produced in the base bronchial exercise tension first agent effect obviously. Plasma protein combined rate of 99%, urinary excretion is 10% of the oral dose, stool excretion was 89%, the elimination half-life of about 10 h. Pharmacokinetic no significant differences in the normal people and patients with renal damage. Take with food when the majority of patients (75%) of reduced bioavailability, the reduction of 40%.
In asthma pathophysiology of the disease, think leukotriene product (LT) and its receptor to produce including the effect of smooth muscle contraction, airway edema and inflammatory cells activity changes (such as acidophilic cell lung infiltrates) are associated with the signs and symptoms of asthma. Drug as an anti-inflammatory drug, can reduce the inflammatory mediators. Drugs as a strong oral peptide LTC4, LTD4 and LTE4 allergic reactions such as slow reaction substance leukotriene receptor antagonist, belong to the competitive inhibition, has the characteristics of high selectivity. In vitro studies have shown that this drug antagonism in the human body the conduction of all three leukotriene polypeptide contraction of airway smooth muscle activity (leukotriene C4, D4 and E4), and the same degree. Animal experiments showed that the effect of drugs mainly: effectively prevent leukotriene peptides due to increased vascular permeability, which can cause airway edema; Inhibition of leukotriene polypeptide produced by airway eosinophilia cell infiltration. Clinical studies also demonstrated the specificity of the drug, only on leukotriene receptor, but does not affect the prostaglandins, thromboxane and histamine and acetylcholine receptors. , according to the verified by clinical medicine with anti-inflammatory properties, 5 doses of the drug can reduce airway cells caused by antigen stimulation and non cell inflammatory substances. Placebo-controlled study found that the antigens stimulate 48 hr after bronchoalveolar lavage, zafirlukast over, inhibit acidophilic cells, lymphocytes, and the rise of tissue cells, and to reduce the alveolar macrophage stimulation produced by peroxide. Drugs can inhibit airway hyperresponsiveness antigen stimulate and platelet active factor cause bronchospasm.
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