By Ransdell Pierson
NEW YORK, Jan 13 (Reuters) - U.S. regulators on Tuesday said their review of clinical trials does not suggest Merck & Co’s (MRK.N) Singulair asthma drug or similar medicines cause suicide or suicidal thought, although the data were inadequate to draw a firm conclusion.
However, the U.S. Food and Drug Administration said it was continuing to review the data to determine if the class of drugs cause other psychiatric problems, including mood and behavioral changes. The agency noted it may take months to conclude that analysis and report its findings.
“If the FDA safety review leads to a stern warning about behavioral changes in the Singulair label, this could frighten users of the drug or their parents and give Merck’s competitors ammunition to attack the brand,” Sanford Bernstein analyst Tim Anderson said in a research note.
The FDA last March said it would conduct a 9-month review of safety data that raised concerns that Singulair (montelukast) might be linked to suicidal thought, suicide and behavioral and mood side effects.
The agency also studied trials involving two other medicines that work by blocking inflammation-causing proteins called leukotrienes, AstraZeneca Pls’s (AZN.L) Accolate (zafirlukast) and Zyflo (zileuton) sold by Cornerstone Therapeutics Inc CRTX.O.
“Although these data do not suggest that montelukast, zafirlukast or zileuton are associated with suicide or suicidal behavior, these clinical trials were not designed specifically to examine neuropsychiatric events,” the FDA said. “As a result, some events may not have been reported.”
Concerns about a possible suicidal link have arrested sales growth of Singulair, Merck’s biggest product with annual sales of almost $4.5 billion.
Singulair’s package insert label was changed in late 2007 to include a warning about such a possible association, based on reports of a few suicides among patients that have taken the medicine during its years on the market, Merck said.
“At the time we did not believe, and we still don’t think a link has been established” between Singulair and the suicides, Scott Korn, a senior safety surveillance executive for Merck, said on Tuesday after the FDA issued its partial findings.
The FDA said it had reviewed results of 41 placebo-controlled trials involving Singulair conducted among patients 6 years of age and older.
“One adult patient out of 9929 patients treated with (Singulair) had suicidal ideation and there were no completed suicides,” the agency said. It said no patients taking placebos in the Singulair trials had suicidal thoughts or committed suicide.
No patients taking Accolate in 45 trials had suicidal thoughts or completed suicide, while one patient taking a placebo in the trials tried suicide and another had suicidal thoughts, the FDA said.
No patients in 11 Zyflo trials, either those taking the drug or a placebo, had suicidal thoughts or completed suicide, the FDA said. (Additional reporting by Lisa Richwine in Washington; Editing by Bernard Orr)