Identify the drug that functions as a leukotriene receptor antagonist.

Explanation

Montelukast is a leukotriene receptor antagonist used to manage asthma and allergic rhinitis. Zileuton inhibits leukotriene synthesis but is not an antagonist. Nedocromil is a mast cell stabilizer, and Misoprostol is a prostaglandin analogue with no leukotriene antagonist activity.