D4 in the lungs resulting in decreased inflammation and relaxation of smooth muscle. Montelukast functions as a leukotriene receptor antagonist (cysteinyl leukotriene receptors) and consequently opposes the function of these inflammatory mediators; leukotrienes are produced by the immune system and serve to promote bronchoconstriction, inflammation, microvascular permeability, and mucus secretion in asthma and COPD. Leukotriene receptor antagonists are sometimes colloquially referred to as leukasts. Two genes of interest are ALOX5 and LTC4S, which catalyze two major steps in the biosynthetic pathway of leukotrienes. Montelukast may affect nerve remyelination in combination with Pexidartinib and this may cause clinical benefits or side effects. Patents Singulair was covered by U.S. Patent No. 5,565,473 which expired on 3 August 2012. The same day, the FDA approved several generic versions of montelukast. The United States Patent and Trademark Office launched a reexamination of the patent covering Singulair on 28 May 2009. The decision was driven by the discovery of references that were not included in the original patent application process. The references were submitted through Article One Partners, an online research community focused on finding literature relating to existing patents. The references included a scientific article produced by a Merck employee on the active ingredient in Singulair. A previously filed patent had been submitted in the same technology area. Seven months later the U.S. Patent and Trademark Office determined that the patent in question was valid based on the initial reexamination and new information provided, submitting their decision on 17 December 2009. Use with loratadine Schering-Plough and Merck sought permission to market a combined tablet with loratadine and montelukast. However, the FDA has found no benefit from a combined pill for seasonal allergies over taking the two drugs in combination, and on 25 April 2008, issued a not-approvable letter for the combination. Names The Mont in montelukast stands for Montreal, the place where Merck (MSD) developed the drug. Montelukast is sold under a variety of brand names including Monalast (Ziska Pharmaceuticals Ltd) Montenaaf (NAAFCO Pharma) Montelon-10 (Apex), Montene (Square), Montair-10, Montelo-10, Monteflo, and Tukast L in India, Reversair (ACI Bangladesh), Monas, Miralust, Montiva, Provair, Montril, Lumona, Lumenta, Arokast and Trilock in Bangladesh, Ventair in Nepal, Montika in Pakistan, Montelair in Brazil, Zykast in the Philippines though combined with levocetirizine, Desmont, Levmont, Aircomb and Notta in Turkey, Topraz in South Africa and AirOn in Venezuela. References External links Alkene derivatives Chloroarenes Cyclopropanes CYP2C8 inhibitors Leukotriene antagonists