All four drugs are leukotriene inhibitors, which affect the leukotriene pathway, which is involved in the body's response to inflammatory stimuli (such as breathing in an allergen).
The FDA notes that some patients using those drugs have reported neuropsychiatric events (behavior or mood changes) including agitation, aggression, anxiousness, dream abnormalities and hallucinations, depression, insomnia, irritability, restlessness, suicidal thinking and behavior (including suicide), and tremor.
The FDA has already reviewed data from clinical trials about suicide risk in patients taking leukotriene inhibitors.
In that review, which the FDA released in January 2009, the FDA said it found no sign of a link between Singulair, Accolate, Zyflo, or Zyflo CR and suicide risk. At the time, the FDA said it was still reviewing clinical data on other behavioral and mood events.
On its web site, the FDA has posted the following advice about leukotriene inhibitors for patients and health care providers:
Patients should talk with their health care provider if these events occur.
Health care professionals should consider discontinuing these medications if patients develop neuropsychiatric symptoms.
Singulair is made by the drug company Merck. In a statement posted on its web site, Merck says that it has updated Singulair's prescribing information about adverse events reported after the drug went on the market, including the types of neuropsychiatric events mentioned today by the FDA.
"Merck will continue to work with the FDA to revise the prescribing information for Singulair in the United States to include a precaution related to those events," states Merck, adding that it is "confident in the safety and efficacy of Singulair, a medicine that has been prescribed to tens of millions of patients with asthma and allergic rhinitis since its approval more than 11 years ago."
Accolate is made by AstraZeneca. Zyflo and Zyflo CR are made by Cornerstone Pharmaceuticals. Those drug companies were not immediately available for comment on the FDA's label change request.