Blockbuster Asthma Drug Singulair Receives Generic Competition

Generic versions of Merck's pharmaceutical blockbuster Singulair (montelukast sodium) are now available to consumers, making it the latest product to fall off the so-called 'patent cliff,' the US Food and Drug Administration (FDA) announced on 3 August.

The drug is used by asthma and allergy sufferers to reduce inflammation, and was Merck's most lucrative, bringing in sales of up to $5 billion per year. The company is expected to lose much of its market share to its new generic competitors, 10 of which were approved by FDA.

The companies approved by FDA to market the drug are Apotex Inc., Aurobindo Pharma, Endo Pharmaceuticals, Glenmark Generics, Kudco Ireland Inc., Mylan Inc., Roxane Laboratories, Sandoz Inc., Teva Pharmaceuticals Inc., and Torrent Pharmaceuticals.

The drug is one of the last drugs to fall off the "patent cliff," so named because of the large number of high-grossing pharmaceutical products losing patent exclusivity around the same time. The loss of exclusivity has put the onus on companies to find alternate sources of income in the form of new products and partnerships, with varying degrees of success.

The two remaining blockbusters set to lose exclusivity are Amgen's Aranesp and AstraZeneca's Nexium, both of which lose their patent protection in 2014.