| Indication |
For the prophylaxis and chronic treatment of asthma. |
| Pharmacodynamics |
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. |
| Mechanism of action |
Zafirlukast is a selective and competitive receptor antagonist of leukotriene D4 and E4 (LTD4
and LTE4), components of slow-reacting substance of anaphylaxis (SRSA).
Cysteinyl leukotriene production and receptor occupation have been
correlated with the pathophysiology of asthma, including airway edema,
smooth muscle constriction, and altered cellular activity associated
with the inflammatory process, which contribute to the signs and
symptoms of asthma. |
| Absorption |
Rapidly absorbed following oral administration, reduced following a high-fat or high-protein meal. |
| Volume of distribution |
|
| Protein binding |
99% |
| Metabolism |
Hepatic |
| Route of elimination |
The most common metabolic products are hydroxylated metabolites which are excreted in the feces. |
| Half life |
10 hours |
| Clearance |
- apparent oral cl=20 L/h
- 11.4 L/h [7-11 yrs]
- 9.2 L/h [5-6 yrs]
|
| Toxicity |
Side effects include rash and upset stomach. |
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