Montelukast (trade name Singulair) is a leukotriene receptor antagonist (LTRA) used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergies. Montelukast comes as a tablet, a chewable tablet, and granules to take by mouth. Montelukast is usually taken once a day with or without food. Montelukast is a CysLT1 antagonist; 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 mechanism of action, it is not useful in the treatment of acute asthma attacks.
The Mont in Montelukast stands for Montreal, the place where Merck (MSD) developed the drug.
While, Levocetirizine is used for allergy symptoms including watery eyes, runny nose, sneezing, hives, and itching. The manufacturers claim it to be more effective with fewer side effects than previous second-generation drugs; however, there have been no published studies supporting this assertion. A study part-funded by the manufacturer UCB concluded it may be more effective than some other second- and third-generation anti-histamines, but did not compare it to cetirizine.
