Asthma begins in childhood. Its prevalence and incidence is increasing worldwide and is considered as the most common chronic childhood disease. Longitudinal studies of Martinez et al shows that 40% of children who wheeze before the age of 3 years will continue to wheeze when they reach the age of six years of life. Unfortunately, children present their symptoms before the age of 5 years. In the Philippines the prevalence of asthma in children is 16%.
Asthma is an inflammatory disorder of the airways where cells (mast, neutrophils, macrophages and eosinophils) are believed to release inflammatory mediators to initiate and perpetuate these inflammatory reactions within the airways. The inflammation within the airways is responsible for widespread but variable airflow obstruction which is oftentimes reversible with or without treatment and airway hyperresponsiveness and the disease presents to the clinicians as cough, wheeze, shortness of breath and chest tightness. Asthma therefore is a multi factorial disease involving bronchospasm, hyperreactivity, chronic and acute inflammation and airway remodeling. There are a number of risk factors in the development of asthma in children among them are (1) positive family history for asthma, atopy and allergy,(2) maternal smoking during pregnancy,(3) exposure to cigarette smoke and other indoor and outdoor pollutants (4) RSV bronchiolitis in the first year of life. We are all aware that 25-30% of children who have suffered from bronchiolitis in the first year of life will develop asthma.
In the management of bronchial asthma in children, one has to classify the disease into the disease categories of either: intermittent and persistent asthma based on the frequency of the symptoms. Patients belonging to the intermittent asthma does category does not warrant maintenance therapy while patients belonging to the persistent asthma warrants maintenance therapy. Inhaled corticosteroid is the cornerstone in the management of persistent asthma be it mild, moderate or severe. A review of 23 randomized, placebo controlled studies using various types of inhaled corticosteroids: Fluticasone propionate (FP), Budesonide (BUD), Beclomethasone di/monopropionate (BDP/BMP) and Triamcinolone acetonamide (TAA) have shown that inhaled corticosteroids is efficacious in controlling the symptoms of asthma. However, in general its use is not very much accepted by pediatricians because of certain "fears" or "phobias" of inhaled corticosteroids in particular on height, adrenal suppression and bone demineralization.
A physician would not harbor fear in using inhaled corticosteroids if he/she is well versed with adequate knowledge on the pharmacokinetics of inhaled steroids and this involves water solubility, volume distribution, clearance, half life of the drug as these will determine the dosing intervals of the drug.
The results of the cohort study of Agertoft and Pedersen published in 2000 had clearly shown that children on inhaled steroid for 3-13 years have achieved the final expected adult height. Knenometric studies (short term growth studies) have shown that growth suppression is more prominent in children receiving oral corticosteroids at the dose of 2.0mg and 5.0 mg compared to children receiving placebo. Growth suppression is more prominent among children receiving oral corticosteroids compared to inhaled corticosteroids. Four short term studies and 6 medium term studies (randomized, placebo controlled and parallel group studies) have shown that long term control can be achieved with the use of low dose inhaled corticosteroids and are not associated with bioactivity and effects on growth. A review of 13 dose response placebo-controlled studies comparing three inhaled corticosteroids (FP, BUD and TAA) these studies shows dose related adrenal suppression. A review of 9 randomized-placebo controlled studies have shown a dose related suppression of osteocalcin however, the suppression is more significant among those subjects receiving oral corticosteroid compared to inhaled corticosteroids.
Inhaled corticosteroids have remained as the mainstay in the management of persistent asthma and literatures are bountiful to support this claim but I would venture to say that inhaled corticosteroids could be used in the management of asthma in acute exacerbation. Several studies have been made. The first Filipino study done in 1994 have shown that inhaled steroids combined with β2-agonist can control the symptoms of asthma after three doses (total ICS dose of 1500µg) can improve pulmonary function (PEFR) within an hour after the initiation of therapy and have reduced the admission rates. Studies by Ellull-Micallef,1983 have shown that inhaled corticosteroid has rapid onset of action as prednisolone. Study of Devidayal, 1999 shows that clinical symptoms score (Pulmonary Index Score), the heart rate, respiratory rate, PEF improved within an hour after the initiation of therapy with ICS. Other study by Pagiarro on the effect of ICS after an allergen challenge shows that PEFR improved within two hours after the initiation of therapy and improvement was maintained over time compared to placebo. ICS has an oral steroid "sparing" effect as studied by Foresi et al, 2000.
In conclusion, inhaled corticosteroids is the mainstay in the management of persistent asthma. However, one has to be aware that he/she has to use the lowest dose that can control the symptoms of asthma to prevent the occurrence of the unwanted side effects. It could be used in the management of asthma in acute at the emergency room. ICS combined with β-2 agonist has good benefits when used in the management of asthma in acute exacerbation.