Researchers combined data from three blinded, case-control studies involving 1,352 children and adults who took either Singulair or placebo.
In fact, the drug seemed to have an opposite effect early in treatment in one trial, with Singulair users scoring higher than placebo users in tests designed to measure emotional status.
Approved by the FDA a decade ago, Singulair has become one of drugmaker Merck's top-selling products, with sales of $4.4 billion last year.
But last March, FDA officials launched an investigation of largely anecdotal reports suggesting a link between the drug and suicidal thoughts and behaviors. The investigation was expected to take nine months.
ALA Chief Medical Officer Norman Edelman, MD, says the new analysis should reassure the millions of people who take Singulair.
"I think there is good evidence that Singulair does not cause depression," he tells WebMD. "We can't say this with absolute certainty, but this goes a long way toward answering the question."
The analysis will be presented in a letter to be published in an upcoming issue of the Journal of Allergy and Clinical Immunology.
Researchers Janet Holbrook, PhD, and Raida Harik-Khan, PhD, combined data from the three ALA-funded trials conducted at 20 research centers across the country.
The original aim of the studies, which included children and adults, was to determine how best to manage asthma symptoms with available treatments, Edelman says. But the studies also included quality of life and emotional well-being assessments for 536 patients treated with Singulair and 816 patients who did not take Singulair.
Adults in the studies were followed for two to 24 weeks and the children were followed for four to 16 weeks.
There were no reports of psychiatric problems, depressive episodes, or suicide among any of the study participants who took Singulair.
None of the trials showed evidence of significant deterioration of emotional well-being in adults or children who took the drug. Compared to people who didn't take the drug, Singulair users showed more improvement in emotional well-being after two weeks of treatment in one trial, but the difference did not last.
"These findings lead us to conclude that despite the recent publicity regarding the adverse effects of (Singulair) on suicide or emotional well-being, we did not find evidence to suggest that this is a general concern," the researchers write.
Drugmaker: Findings No Surprise
Merck spokesman Ian McConnell says the finding comes as no surprise.
"This independent study adds further support to the large body of evidence for the safety of Singulair," he tells WebMD.
Late in March, after the FDA investigation was announced, Merck senior director of clinical research George Philip, MD, told WebMD that there were no reports of suicides in 40 clinical studies involving 11,000 patients who took Singulair.
Singulair belongs to a class of drugs called leukotriene receptor antagonists. The FDA is reviewing post-marketing data on other drugs in the class to determine if further investigation is warranted.
Two of the nation's largest asthma organizations also weighed in on the Singulair-suicide issue after the FDA investigation was announced.
"There are no data from well-designed studies to indicate a link between Singulair and suicide," officials with the American College of Allergy, Asthma and Immunology and the American Academy of Allergy, Asthma and Immunology noted in a joint statement.
"The concern expressed by the FDA is based entirely on case reports and there is no indication that such effects apply to other leukotriene-modifying medications."
The ACAAI and AAAAI statement further noted that, "based on the information currently available, patients taking Singulair should continue to take the medication as prescribed provided 1): the patient and physician feel the medication is effective; and 2) the patient does not experience any suicidal behavior or thoughts."