Irritancy isoenzymes

Two clinically distinct cysteinyl leukotriene receptor antagonists (zafirlukast and montelukast) and one inhihitor of leukotriene synthesis (zUeuton) have been available in the United States since 1996 for both children and adults with persistent asthma. In challenge studies, they reduce allergen-, exercise-, cold-air hyperventilation-, irritant-, and aspirin-induced asthma. Chnical use of zileuton is limited owing to the need for four-times-daily dosing, the potential for elevated liver enzymes (especially in the first 3 months of therapy), and the potential inhibition of drugs metabolized by the CYP3A4 isoenzymes. ... 

---