| Item |
Information |
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Drug Groups
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approved; investigational |
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Description
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Zafirlukast is an oral leukotriene receptor antagonist (LTRA) for the maintenance treatment of asthma, often used in conjunction with an inhaled steroid and/or long-acting bronchodilator. It is available as a tablet and is usually dosed twice daily. Another leukotriene receptor antagonist is montelukast (Singulair), which is usually taken just once daily.
Zafirlukast blocks the action of the cysteinyl leukotrienes on the CysLT1 receptors, thus reducing constriction of the airways, build-up of mucus in the lungs and inflammation of the breathing passages.
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| Indication |
For the prophylaxis and chronic treatment of asthma. |
| Pharmacology |
Zafirlukast is a synthetic, selective peptide leukotriene receptor antagonist (LTRA) indicated for the prophylaxis and chronic treatment of asthma. Patients with asthma were found in one study to be 25-100 times more sensitive to the bronchoconstricting activity of inhaled LTD4 than nonasthmatic subjects. In vitro studies demonstrated that zafirlukast antagonized the contractile activity of three leukotrienes (LTC4, LTD4 and LTE4) in conducting airway smooth muscle from laboratory animals and humans. Zafirlukast prevented intradermal LTD4-induced increases in cutaneous vascular permeability and inhibited inhaled LTD4-induced influx of eosinophils into animal lungs. |
| Toxicity |
Side effects include rash and upset stomach. |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Hepatic |
| Absorption |
Rapidly absorbed following oral administration, reduced following a high-fat or high-protein meal. |
| Half Life |
10 hours |
| Protein Binding |
99% |
| Elimination |
The most common metabolic products are hydroxylated metabolites which are excreted in the feces. |
| Distribution |
* 70 L |
| Clearance |
* apparent oral cl=20 L/h
* 11.4 L/h [7-11 yrs]
* 9.2 L/h [5-6 yrs] |
| External Links |
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