Asthma (Part 3)
Other treatment options
Leukotriene receptor antagonists (montelukast): an oral drug that acts by blocking part of the chemical reaction involved in inflammation of the airways. Montelukast is particularly beneficial for two types of asthma:
- asthma predominantly induced by exercise
- Asthma associated with allergic rhinitis.
Other types of asthma where montelukast has shown efficacy include asthma in obese patients, asthma in smokers, aspirin-induced asthma, and viral-induced wheezing episodes. Leukotriene receptor agonists help allergic rhinitis symptoms (eg. hayfever) too.
Theophylline: helps widen the airways by relaxing the muscles around them. Theophylline is known to cause potential side effects, including headaches, nausea, insomnia, vomiting, irritability, and stomach upsets. These can usually be avoided by adjusting the dose. It has a narrow therapeutic index meaning the balance between sub-optimal dosage and overdosage is difficult to manage.
Macrolides (e.g.) Azithromycin: Oral macrolide therapy has been shown to improve quality of life in people with asthma. Lower-dose regimens (e.g., Azithromycin 250mg or 500mg three times a week) have possible non-antimicrobial mode of action, possibly as a steroid-sparing agent.
When can therapy be reduced?
Good control is reflected by the absence of night-time symptoms, no symptoms on exercise and the use of relievers less than three times a week. Patients should be maintained on the lowest effective dose of inhaled steroids, with reductions of 25-50% being considered every three months.
Biologics for severe Asthma
Biologics are a new class of drugs called monoclonal antibodies that are licenced for severe asthma. They reduce the inflammation from the in the respiratory tract. Only respiratory specialists can prescribe biologics.
Most biologics are given by subcutaneous injection once or twice a month. All biologics are an add-on option and do not replace existing reliever and preventer medication, but patients should eventually be able to reduce the dosage of existing therapies such as inhaled corticosteroids. Biologics are available to target the two subtypes of Type-2 Severe Asthma (i.e.) allergic (IgE-mediated) asthma and eosinophilic asthma
Biologic therapy drugs for severe asthma include:
- Omalizumab (Xolair®)
- Mepolizumab (Nucala®)
- Reslizumab (Cinqair®)
- Benralizumab (Fasenra®)
- Dupilumab (Dupixent®)
Of the 5 biologics listed above, Omalizumab is an anti-IgE agent, and the other 4 biologics are anti eosinophilic agents.
Biologics, are expensive (average cost is €15,000 per year), require frequent monitoring and limited to specific types of severe asthma meaning use is limited to strict protocols.
In clinical trials, all 5 biologics reduced annualised exacerbation rates by at least 50% and they all improved asthma symptom scores, lung function and quality of life and allowed reductions in maintenance oral corticosteroids while maintaining a favourable safety profile. Side effects of biologics include headache, pain, redness, itching, and/or a burning sensation at the injection site
Availability of Biologics for Asthma in Ireland
Biologics in Ireland are not available on prescription form your doctor in the manner of other drugs. Biologics for asthma are paid for directly out of hospital budgets which limits their availability as hospitals only have limited budgets meaning respiratory consultants have to limit prescribing dependant on budget. The Asthma Society of Ireland is leading a campaign for the Government to expand the national fund for biologic medication for severe asthma to allow greater patient access.
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