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  • Medication supply issues: Mast cell activation syndrome (MCAS)

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    • UK
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    • Pre-existing
    • Original author
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    • 13/05/24
    • Everyone


    Joy Mason is the Director of Operations, Services and Engagement at Mast Cell Action. In this blog, Joy tells us more about Mast Cell Activation Syndrome and how medication supply issues are impacting people’s lives and causing avoidable harm. 


    What is Mast Cell Activation Syndrome?

    Mast Cell Activation Syndrome (MCAS) is a condition which can develop in children or adults. In people affected by MCAS, chemicals called mast cell mediators are released too frequently or abundantly, and/or in response to triggers that are not typically considered to be harmful. Triggers can include fragrances, exercise, stress and changes in temperature.


    MCAS symptoms are often unpleasant, debilitating and wide-ranging - affecting different parts of the body at the same time. Symptoms can come and go and may often change over time within the same person. This can make it difficult to identify specific triggers, and the number of triggers and severity of symptoms may continue to increase as the condition progresses. People who have MCAS are at an increased risk of having an anaphylactic reaction after encountering a trigger. Anaphylaxis is a potentially life-threatening allergic reaction.


    MCAS medications

    Multiple medicines can be used to help alleviate the symptoms of MCAS and to stabilise those affected. These include mast cell stabilisers; which help restore stability to the mast cell and reduce its reactivity to different triggers, and mediator blockers; which block the release or the effect of different mediators released by the mast cell.

    A medical treatment that works for one person may not work for another and the response to treatment is not always predictable. The availability of treatments varies, and some are reserved only for the most severe cases of MCAS.

    Medication supply issues

    In recent years, medication supply issues relating to MCAS have increased.

    • 45% of our community tell us they are prescribed adrenaline auto-injectors, there have been multiple supply issues with these in recent years.
    • 32% of our community tell us they are prescribed ketotifen. Ketotifen is regularly out of stock and unavailable for long periods. This webpage set up by UK Masto, aims to keep patients, pharmacists and doctors up to date with the latest information on how to obtain ketotifen.    
    • The Intal inhaler was discontinued several years ago. Multiple members of our community found this extremely helpful in stabilising symptoms.
    • 37% of our community tell us they are prescribed Sodium Cromoglicate. Again, there have been multiple supply issues. This webpage set up by UK Masto, aims to keep patients, pharmacists and doctors up to date with the latest information on Sodium Cromoglicate.
    • Due to reactions to excipients, it is common for people with MCAS not to tolerate all variations of a medication but they may be able to safely take specific brands. Where medication stock issues arise, this can make accessing safe brands of medication more complicated and means that even when other brands are available, our community can not safely access medications.[1]

    The impact on patients

    Medical treatment for MCAS is 2-fold; attempting to stabilise the mast cells alongside treating the symptoms.

    If medications become unavailable, this could lead to a range of debilitating, unpleasant and sometimes life-threatening symptoms, which could have been avoided.

    “It can be a full-time job trying to find a chemist with my medication in stock. Calling different pharmacies to ask if they have or can get hold of specific brands of medication is so time-consuming. Then I have to ask the doctor to split my prescription and send different ones to different chemists – all of this while feeling unwell and juggling multiple hospital appointments. It’s a lot!”

    “My son can only take one brand of fexofenadine – the others all have a colouring that makes him react. Every month, I anticipate potential stock issues as they are so common – will they be able to provide his safe medication? This is the difference between him being at school or being too poorly to go. Sometimes this is the difference between an A&E visit or being able to manage symptoms at home. It’s scary that our fate seems to sit in the unknown”.

    What needs to happen?

    Medications, such as Ketotifen, going out of stock when there is no alternative has a huge impact on the well-being of our community. These stock issues are common and it is scary for many people with MCAS who don’t know if they will be able to access their medication in the coming months.

    • Consistent production and smooth supply chains with limited disruption would limit shortages.
    • A long-term commitment from pharmaceutical companies to supporting patients with rare diseases by consistently prioritising medication availability and affordability would be hugely beneficial to thousands of people living with complex medical conditions.
    • Expanding compounding services in the UK to enable the provision of customised formulations for patients on the NHS when standard medications are unavailable or unsuitable would alleviate the pressure caused by supply issues.

    Final thoughts

    Managing MCAS takes a dedicated step-wise, delicate approach. Tweaking medications is complex. Triggers can change – meaning that a person could react to a medication which they have previously tolerated, and reactions to excipients often prevent people from accessing alternative brands when availability is challenged.

    Additionally, stress is a trigger for many people with MCAS. Managing medications and struggling with supply issues can be stressful and anxiety-provoking.

    [1] Molderings, GJ, Haenisch, B, Brettner, S et al. Pharmacological treatment options for mast cell activation disease. Naunyn-Schmiedeberg's Arch Pharmacol 389, 671–694 (2016).

    Related content: Medication supply issues: A pharmacist’s perspective

    Join the conversation

    Have you (or a loved one) ever been prescribed medication that you were then unable to get hold of at the pharmacy? 

    • Was there an impact on your health (physical and mental)? 
    • Were you told the reason for it not being available? 
    • Was the issue resolved? If so, how long did it take?If you are still impacted by medication supply issues, have you been told when you will be able to access them again?

    To help us understand how these issues impact the lives of patients and families, please share your experience and insights in our community forum. You'll need to register with the hub first, its free and easy to do. Or you can email us at content@pslhub.org.

    We would also like to hear from pharmacists working in community or hospital settings, and others who have insights to share on this issue. What barriers and challenges have you seen around medication availability? Is there anything that can be done to improve wider systems or processes?

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