Qustions and Answers in ASTHMA MANAGEMENT
Qustions and Answers in ASTHMA MANAGEMENT
Dr. Tarek Safwat
MD,FCCP Professor of Pulmonary Diseases, Ain Shams University.
President of The Egyptian .Scientific Society of Bronchology
Why is asthma on the increase?
The rise in asthma prevalence appears to be a part of an increase in
all atopic ( allergic ) disease including allergic rhinitis ( hay fever) and
atopic dermatitis ( eczyma)
Researchers believe that the prevalence of atopic disease is now
doubling approximately every 10 years faster than ever before.
The precise reasons for this dramatic increase are still uncertain, but the
timing suggests it is associated with modern living and environmental factors
of some kind. Several possible causes have been put forward.
Initially, many researchers believed that atmospheric pollution could be
responsible but this hypothesis is not supported by the epidemiological
findings.
There is no evidence that allergic disease are more common in areas that
are more polluted by traffic or industrial pollutants.
Another possibility is that people are increasingly being exposed to high
levels of certain allergens such as house dust mite or pet allergens.
However there is no strong evidence that allergen exposure has significantly
increased throughout the world and the increase in atopy is not specific for any
particular allergen .
Is it a genetic disease?
Asthma clearly runs in families largely because atopy is inherited.
We now know that many genes are important in determining atopy
and that the actual genes involved differ between populations, this may
explain why there is often so little agreement between the results of
research in different countries and among different populations
What is the nature of Asthma?
The widespread recognition is that asthma is a chronic
inflammatory disease of the airways and can be controlled
with regular antiinflammatory treatment.
What are the different modalities
in management?
1- Glucocorticoids (ICS) are currently the most effective
anti inflammatory medications for the treatment of asthma.
Studies have demonstrated their efficacy in improving lung function decreasing airway hyper responsiveness
reducing symptoms reducing frequency and severity of exacerbation and improving quality of life.
Glucocorticosteroids are the preferred treatment for patients with persistent asthma at all levels of severity.
Glucocorticosteroids differ in potency and bioavailability after inhalation.
2- Long acting inhaled B2- agonists (LABAs) as formoterol and salmetrol have a duration of acting lasting about 12 hours, are bronchodilators that relax airway smooth muscle, enhance mucociliary clearance, decrease vascular permeability, and may modulate mediator release from mast cells and basophils. In fact a small anti inflammatory effect has been reported with long term use. Therapy with long acting inhaled B2-agonists produces bronchodiltation comparable to, or better than oral therapy.
Clinical pharmacology studies have shown that the duration of the bronchoprotective effect provided by long acting inhaled B2-agonists decreases when these medications are used on regular basis as monotherapy .
Long-acting inhaled B2-agonists may also be used to prevent exercise induced bronchospasm and may provide longer protection than short - acting inhaled B2 agonists.
Formoterol and salmterol provide a similar duration of bronchodilation and protection against bronchoconstrictors, but there are pharmacological differences between them.
Formoterol has a more rapid onset of action than salmetrol, which may make formoterol suitable for symptom relief as well as symptom prevention during exercise. Can we combine both LABA &
ICS for more benefits?
Addition of LABAs to a daily regimen of inhaled corticosteroids improves symptom scores, decreases nocturnal asthma, improves lung function, decreases the use of short acting inhaled B2 agonists and reduces the number of exacerbation.
Several studies have now shown that adding a long
acting inhaled B2 agonists as formoterol in patients
whose asthma is not controlled on either low or high
doses of ICS results in better control of asthma in terms
of lung function and symptoms than increasing the dose
of inhaled corticosteroids 2- fold or more.
Controlled studies have shown that delivering LABA
& ICS separately is effective due to prior inhalation
of LABA will promote the deep inhalation of ICS into
peripheral lung regions because the ability of inhaled
drug to penetrate into the peripheral regions is limited,
particularly in patients with airflow obstruction.
In addition asthma severity fluctuates over time
consequently, frequent step-up and step-down changes
in dosing may be necessary to meet the patient's
needs over time, to increase or reduce the dose of
bronchodilator and/or corticosteroid.
This image showed deep penetration of 99 mTc-labeled
(Green dots) treatment after LABA inhalation ( Formoterol )