Concern expressed over asthma drug Singulair

U.S. regulators concluded that Merck & Co.'s top-sulling asthma drug, Singulair, should come with a caution about psychiatric problems.  The caution would also apply to Accolate, manufactured by AstraZeneca, Zyflo and Zyflo CR, made by Cornerstone Therapeutics.  A "caution" is less serious than a warning, according to Reuters News Service, and applies to problems incluidng agitation, aggression, suicidal ideation, depression, insomnia and irritability, which may be associated with the medications in some patients.  Singulair is prescribed to tens of millions of patients since approval in 1998 and has annual sales of $4.5 billion dollars.