Government scientists have discovered a potential link between a popular asthma medication, originally marketed by Merck & Co, and severe mental health issues in some patients. The drug, known as Singulair and generically as montelukast, has been found to interact with several brain receptors crucial to psychiatric functioning.
Singulair, launched in 1998, was a significant product for Merck, providing an alternative to inhalers. The company initially advertised the drug’s side effects as being as harmless as those of a sugar pill, and claimed that its distribution in the brain was minimal. Despite this, the drug is still prescribed to millions of adults and children annually.
By 2019, thousands of reports of neuropsychiatric episodes, including numerous suicides, had been reported by patients prescribed Singulair. These reports were found on internet forums and in the US Food and Drug Administration’s (FDA) tracking system. While these reports do not definitively establish a causal relationship between the drug and these side effects, they are used by the FDA to determine if further investigation into a drug’s risks is necessary.
After years of analysis and new scientific research, the FDA added a “black box” warning to the montelukast prescribing label in 2020. This warning highlighted serious mental health risks, including suicidal thoughts or actions. Around the same time, the FDA assembled a team of internal experts to investigate why the drug might trigger neuropsychiatric side effects.
Preliminary results from the group’s work were presented at the American College of Toxicology meeting in Austin, Texas. The FDA has stated that it does not plan to update the drug label based on the data from this presentation.
The behavior of montelukast appears to be similar to other drugs known to have neuropsychiatric effects, such as the antipsychotic risperidone. The FDA has cautioned that its studies are ongoing, and results have not been finalized.
When the FDA added the black box warning, it cited research from Julia Marschallinger and Ludwig Aigner at Austria’s Institute of Molecular Regenerative Medicine. The two scientists told Reuters that the new data showed significant quantities of montelukast present in the brain. The receptors involved play a role in governing mood, impulse control, cognition, and sleep, among other functions.
The research does not show whether that binding mechanism leads directly to harmful effects in individual patients, or who is particularly at risk. However, Marschallinger said the new data supports reports from people who reported suffering side effects.
Organon, a Merck spinoff that now markets Singulair, said in a statement it is confident in the drug’s safety profile. The company stated that the product label for Singulair contains appropriate information regarding Singulair benefits, risks, and reported adverse reactions.
By 2019, the FDA had recorded 82 suicides linked to Singulair and its generic versions since 1998. At least 31 of those reports involved someone 19 or younger.