UPDATE 1-FDA says Singulair data do not suggest suicide link

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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: Quote, Profile, Research) 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: Quote, Profile, Research) Accolate (zafirlukast) and Zyflo (zileuton) sold by Cornerstone Therapeutics Inc (CRTX.O: Quote, Profile, Research).

"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.