Which of the following anti-asthmatic drugs is leukotriene antagonist?

Ans. a (Montelukast) (Ref. KDT 5th/pg. 222).Zlleuton--A 5-lipoxygenase pathway inhibitor. Blocks conversion of arachidonic acid to leukotrienes.Zafirlukast, montelukast--block leukotriene receptors. Especially good for aspirin-induced asthma.ANTILEUKOTRIENESCysteinyl-leukotrienes are potent bronchoconstrictors, cause microvascular leakage, and increase eosinophilic inflammation through the activation of cys-LT1-receptors. These inflammatory mediators are produced predominantly by mast cells and, to a lesser extent, eosinophils in asthma. Antileukotrienes, such as montelukast and zafirlukast, block cys-LT1 - receptors and provide modest clinical benefit in asthma. They are less effective than ICSs in controlling asthma and have less effect on airway inflammation, but are useful as an add-on therapy. They are given orally once or twice daily and are well tolerated.Drugs used in treatment of bronchial asthma:I. Bronchodilators A. SympathomimeticsAdrenaline, Ephedrine, Isoprenaline, Salbutamol, Terbutaline, Bambuterol, Salmeterol, Formoterol.B. MethylxanthinesTheophylline (anhydrous), Aminophylline, Choline theophyllinate, Hydroxyethyl theophylline,Theophylline ethanolate of piperazine).C AnticholinergicsAtropine methonitrate, Ipratropium bromide, Tiotropiurm bromide.II. Leukotriene antagonistsMontelukast, Zafirlukast.III. Mast cell stabilizersSodium cromoglycate, Nedocromil, Ketotifen.IV. CorticosteroidsA. SystemicHydrocortisone, Prednisolone and others.B. InhaiationalBeclomethasone dipropionate, Budesonide, Fluticasone propionate, Flunisotide.Approaches to Treatment of Bronchial Asthma1. Prevention of Ag:Ab reaction - avoidance of antigen, hyposensitization - possible in extrinsic asthma and if antigen can be identified.2. Suppression of inflammation and bronchial hyperreactivity - corticosteroids.3. Prevention of release of mediators - mast cell stabilizers.4. Antagonism of released mediators - leukotriene antagonists, antihistamines, and PAF antagonists.5. Blockade of constrictor neurotransmitter - anticholinergics.6. Mimicking dilator neurotransmitter - sympathomimetics.7. Directly acting bronchodilators - methylxanthines.Educational Point:# Omalizumab is a blocking antibody that neutralizes circulating IgE without binding to cell-bound IgE; it thus inhibits IgE-mediated reactions.