The FDA began reviewing safety data on those four drugs and suicide, suicidality (suicidal thinking and behavior) and other behavior and mood changes in March 2008.
The agency now concludes that the data "do not suggest" that Singulair, Accolate, Zyflo, or Zyflo CR are associated with suicide or suicidal behavior, although the data came from clinical trials that weren't designed to examine such events.
The FDA reached those conclusions based on data from 41 clinical trials of Singulair, 45 clinical trials of Accolate, and 11 trials of zileuton (the active ingredient in Zyflo and Zylfo CR). Each of those drugs was compared to a placebo, but the studies weren't head-to-head comparisons of the asthma drugs.
The data show no suicides among patients taking any of the asthma drugs and only one case of suicidal thinking in an asthma drug user, which occurred in one out of 9,929 patients treated with Singulair. For comparison, there was one suicide and one case of suicidal thinking in the placebo group in the Accolate trials, and no reports of suicides or suicidal thinking in the zileuton trials.
Singulair is made by the drug company Merck. Accolate is made by the drug company AstraZeneca. Zyflo and Zyflo CR are made by the drug company Cornerstone Therapeutics.
"We're pleased with the conclusions," Alan Ezekowitz, MBChB, DPhil, Merck's senior vice president and franchise head for respiratory diseases, tells WebMD.
Ezekowitz notes that ever since the FDA's review began, the American College of Allergy, Asthma & Immunology and the American Academy of Allergy, Asthma & Immunology have recommended that patients should keep taking their asthma drugs as prescribed and consult their physicians with any questions.
The FDA is still reviewing clinical trial data on other behavioral and mood events related to those asthma drugs, which all affect the leukotriene pathway, which is involved in the body's response to inflammatory stimuli (such as breathing in an allergen).