The US Food and Drug Administration (FDA) is reviewing the safety of Merck & Co’s anti-asthma drug Singulair (montelukast) following reports querying a potential link between the drug’s use and changes to behaviour and mood, suicide, and suicidal thinking and behaviour.

The agency made the announcement yesterday, 27th March, in an Early Communication About an Ongoing Safety Review on its Centre for Drug Evaluation and Research website and stressed it does not mean the FDA has found that the drug causes these symptoms and neither does it mean the agency is advising healthcare professionals to stop prescribing it.

The FDA emphasized it has not reached a conclusion about the drug and whether any regulatory action is necessary, but it is considering it and will announce further updates when more information is forthcoming or further analyses are conducted.

Singulair (montelukast) is a prescription drug used to treat asthma and allergic rhinitis, which is characterized by sneezing, runny, itchy and stuffy nose. The drug belongs to the class known as leukotriene receptor antagonists and is also used to prevent asthma brought on by exercise.

The agency has asked the drug manufacturer to re-evaluate results of clinical trials following enquiries about a possible link between Singulair use and changes in behaviour and mood, suicidality (suicidal thoughts and behaviour) and suicide. The agency itself is reviewing postmarketing reports of a potential link in patients who have been taking the drug.

In the last 12 months, due to adverse events reported during the post-marketing phase, Merck & Co have updated the patient and prescribing information for Singulair three times to alert doctors and patients to the following side effects: tremor, depression, suicidal thinking and behaviour, and anxiousness, said the FDA.

Since last month the FDA and the drug company have been discussing how best to inform patients and doctors about these label changes. The drug company said it is planning face to face meetings with prescribers to tell them about the changes and to give them patient leaflets so they can inform their patients about the risks of taking Singulair. The FDA said the manufacturer’s website for the drug also contains the most current information for prescribers and patients.

Because of the complexity of the investigation, the FDA does not anticipate reaching a conclusion earlier than 9 months’ time, when it will publicly announce the findings.

Until then, doctors and healthcare professionals should monitor any patients taking Singulair for signs of suicidal thinking and behaviour, and any other changes in behaviour and mood.

The FDA stressed that the drug is an effective medication indicated for the treatment of asthma and symptoms of allergic rhinitis and patients should not stop taking it without consulting their doctor about this new information.

The agency is also reviewing post marketing reports of similar potential side effects in other leukotriene receptor antagonists, Accolate, Zyflo, and Zyflo CR to decide if they should also be investigated further.

The FDA asks patients and doctors to report any side effects from the use of Singulair, Accolate, Zyflo, and Zyflo CR to the agency’s MedWatch Adverse Event Reporting program.

Singulair is currently approved in the US for use by adults and children 12 months and over for the relief of symptoms brought on by indoor and outdoor allergies. For outdoor allergies it is approved for use in adults and children down to 2 years old, for indoor allergies the youngest age limit is 6 months.

Merck & Co says the drug is not a replacement for fast acting inhalers for sudden symptoms and patients should continue to take their other asthma medication as prescribed by their doctor and have fast acting medication available.

Click here for latest patient and prescriber information about Singulair (Merck & Co website).

Click here for FDA.

Sources: FDA, Merck & Co.

Written by: Catharine Paddock, PhD