Merck & Co has won U.S. Food and Drug Administration approval to market its once-daily asthma drug, Singulair (montelukast), for the relief of indoor allergies in adults and children six months of age and older.

"Allergic rhinitis is one of the most common allergic conditions today, with approximately 50 million people in the USA suffering some form of the condition," said Gailen Marshall, director of the Division of Clinical Immunology and Allergy at the University of Mississippi Medical Center. "Experts have estimated that 55% to 80% of these patients suffer from perennial, or year round, allergic rhinitis which is commonly triggered by indoor allergens such as dust.

Singulair was cleared for use in hay fever in 2003 and works by blocking leukotrienes, an important contributor to allergy symptoms, rather than the conventional means of targeting histamine.

Sales of Singulair rose 14% to $730 million for the second quarter of this year [[22/07/05a]] and is one of Merck’s most important drugs, particularly in light of the loss of the COX-2 drug Vioxx (rofecoxib) [[01/10/04a]].