Leukotriene Antagonist

Competitive inhibitor of leukotriene synthesis REF: Goodman and Gillman’s 11′ edition p. 478

“Zafirlukast and Montelukast are leukotriene receptor antagonists. Leukotriene-modifying drugs act either as competitive antagonist of leukotriene receptors or by inhibiting the synthesis of leukotriene”

Inhibition of leukotriene production

Out of all the given options, Montelukast is a leukotriene antagonist.

Ref: K D Tripathi Textbook of Pharmacology, 5th Edition, Page 205; Modern Pharmacology With Clinical Applications By Charles R. Craig, Robert E. Stitzel, Pages 465-67

Among the options given only Zafirleukast is leukotriene receptor antagonist. Zileuton is a 5-Lipoxygenase inhibitor, Ketotifen is an antihistaminic (H1) and Omalizumab is a recombinant humanized monoclonal anti-IgE antibody.

Ref: Bronchial Asthma: A Guide for Practical Understanding and Treatment, Springer, 2011, Page 193; Current Review of Asthma, By Michael A. Kaliner – Page 216; Essentials of Medical Pharmacology, KD Tripathi – 5th Edition, Page 205-206; Katzung & Trevor’s Pharmacology 10th Edition, Page 325.

Ans. is ‘a’ i.e., Monteleukast

o Monteleukast and zafirleucast are cystenyl LT, (cys LT,) receptor antagonists.

Ans. is ‘c’ i.e., Aspirin induced asthma

o Leukotrienes antagonists are effective in aspirin induced asthma.

Ans. D: Montelukast

It is usually administered orally.

Montelukast is a CysLT1 antagonist; that is it blocks the action of leukotriene D4 (and secondary ligands LTC4 and LTE4) on the cysteinyl leukotriene receptor CysLT1 in the lungs and bronchial tubes by binding to it.

This reduces the bronchoconstriction otherwise caused by the leukotriene, and results in less inflammation.

Because of its method of operation, it is not useful for the treatment of acute asthma attacks. Again because of its very specific focus of operation, it does not interact with other allergy medications such as theophylline.

Another leukotriene receptor antagonist is zafirlukast.

Zileuton, an asthma drug, blocks leukotriene synthesis by inhibiting 5-lipoxygenase, an enzyme of the eicosanoid synthesis pathway

Ans. B i.e. Montelukast

Ans. is ‘a’ i.e., Leukotriene antagonist

Leukotriene antagonists

• Monteleukast and zafirleucast are cystenyl LT, (cys LT₁) receptor antagonists.
• They are indicated for prophylactic therapy of mild to moderate asthma as alternatives to inhaled glucocorticoids.
• They are more acceptable in children.
• They are not used for terminating asthma episodes.
• They are effective in aspirin induced asthma.
• They are very safe drugs, produce few side effects like headache and rashes.
• Eosinophilia, neuropathy and churg-strauss syndrome are other rare side effects.