Potential Connection Between Merck’s Former Asthma Medication Singulair and Mental Health Issues: Reuters
Recent findings from FDA researchers indicate a molecular connection between Merck’s previously successful asthma medication, montelukast, which is currently marketed by Organon under the brand Singulair, and neuropsychiatric issues. This information was detailed in a report from Reuters.
The agency presented research at the 2024 Annual Meeting of the American College of Toxicology, revealing several unintended effects of montelukast on G-protein coupled receptors and neurotransmitter transporters in the brain, which play significant roles in various psychiatric conditions. The FDA’s findings also confirmed that montelukast penetrates rat brain tissue, supporting earlier studies.
“New data from pharmacology studies using primary human central nervous system cells treated with montelukast and endogenous receptor ligands shed light on the possible molecular pathways impacting central nervous system effects,” highlighted the researchers in their abstract. This is the first time these findings have been publicly shared.
As noted by Reuters, the FDA does not currently plan to modify the montelukast product labeling to include these new insights.
Montelukast functions as a small molecule blocker of leukotriene receptors, primarily located in the airways, which cause bronchoconstriction upon interaction with their ligands. By inhibiting these receptors, montelukast alleviates symptoms associated with asthma and allergic rhinitis. The FDA first approved this medication in 1998, launching it under the Singulair brand.
In subsequent years, Singulair became a top product for Merck, achieving sales exceeding .4 billion in 2001 and accumulating nearly billion in total sales over its market presence, as noted in a 2017 Kiplinger report.
However, by 2019, the FDA had identified thousands of neuropsychiatric adverse events associated with Singulair and generic montelukast formulations. Merck was criticized for allegedly downplaying initial evidence of this safety concern when Singulair was launched, claiming that side effects were generally mild.
As a result of these reports, the FDA instituted a black box warning for the drug in 2020, cautioning patients and healthcare providers about the possible occurrence of “serious neuropsychiatric events” such as agitation, hostility, depression, anxiety, insomnia, and obsessive-compulsive symptoms. Some patients on montelukast have also reported experiencing suicidal thoughts and behavior.
Due to these concerns, the therapeutic benefits of Singulair—and montelukast in general—might not justify its use in treating allergic rhinitis, per its label, which advises reserving its application for individuals with “insufficient response or intolerance” to other treatments.
Following the spin-off from Merck, the medication was transferred to Organon, which stated to Reuters that the current label remains suitable in terms of “benefits, risks and reported adverse events.”