A common asthma medication, currently in use in Belgium among some 159,000 patients, causes many more side-effects than previously thought, according to two Belgian doctors.
Montelukast came onto the market in 1997, specifically for the treatment of asthma, but now increasing used for allergies. The number of people currently being prescribed the drug in Belgium is estimated to be around 159,000.
But according to Dr. Patrik Vankrunkelsven of the university of Leuven, and physician-journalist Marleen Finoulst, writing in the journal Tijdschrift voor Geneeskunde en Gezondheidszorg (paywall), the drug is now responsible for psychiatric side-effects in a majority of the children receiving the drug – 39,000 of the national total of users.
The symptoms concerned are not normally associated with asthma drugs, and include mood and behaviour swings, sleep disturbances, anxiety, aggressive and combative behaviour, depression and even suicide.
According to the US Food and Drug Administration, 82 cases of suicide have been recorded that can be attributed to Montelukast. Of those, 45 were adults (aged over 17), 18 did not report an age and 19 were young people under the age of 18.
In Belgium, some 18 million doses are being taken every year.
"That's a lot," Vankrunkelsven told De Standaard. “Certainly for a drug that has serious side effects and whose added value has been under discussion in recent years. Although it is usually third choice, it is often prescribed, including to children.”
Concern is growing. The European Medicines Agency issued a warning in 2019 of possible neuro-psychiatric events associated with taking the drug. But those warnings do not go to the general public, and have to be communicated via the prescribing physician, who consequently has to be up to date on all the latest information.
In the US, the FDA took the bigger step by issuing a ‘boxed warning’ – which means the danger of side-effects is literally printed in a black box on the drug’s accompanying information leaflet. It may sound like a cosmetic change, but a boxed warning is a red flag to any physician.
To hammer the message home, last year the Federal Agency for Drugs and Medical Products sent a circular to all prescribers informing them of the need to advise patients or the parents of patients of the risks, and the warning signs to look out for.
“But when I talk to fellow doctors about it, most of them have no idea, just like my patients,” said Dr Vankrunkelsven. “I think that the Belgian package leaflets emphasise the side effects far too little. However, I have also had a few young people in my practice who struggled with nightmares and depression,” he said.
“As far as I'm concerned, the drug's drawbacks outweigh the potential benefits.”