| Role in therapy: Inhaled glucocorticosteroids represent the most effective anti-inflammatory therapy for the treatment of persistent asthma. Studies have demonstrated their efficacy in reducing asthma symptoms, improving quality of life, improving lung function, reducing airway hyperresponsiveness, controlling airway inflammation, reducing exacerbations frequency and severity and reducing asthma mortality. However, they do not cure asthma, and when they are discontinued deterioration of clinical control follows within weeks to months in a proportion of patients.
Potency and bioavailability of the various glucocorticosteroids are different, and in
addition, since they are characterized by a relatively flat dose-response curve for plenty
of outcome measures in asthma (symptoms, lung function parameters and airway
hyperresponsiveness), dose comparisons of glucocorticosteroids are difficult. However,
Table 3 lists the estimated equipotent doses of various inhaled corticosteroids.
Table 3: Estimated Equipotent Daily Doses of Inhaled Glucocorticoids for Adults. GINA 2010 Update
Due to the flatness of inhaled
corticosteroids dose-response curves,
a high increase of the dosage would
not provide proportional further
benefits in terms of asthma control,
as shown in Fig. 1. In addition, the
higher the dose, the greater the risk
of side effects.2 Patients should be
treated with a specific dose of ICS,
producing the maximum benefit and
leading to the minimum side effects
(X dose indicated in the picture). This
dose varies on the severity of asthma
and on the type of adopted ICS.
Figure 1: Relation between beneficial and
adverse effects with increasing doses of inhaled
corticosteroids.2
Side effects: Besides steroids local side effects, such as oropharyngeal candidiasis, dysphonia, and occasionally coughing from upper airways irritation, there is also the risk of systemic side effects (easy bruising, adrenal suppression, and decreased bone mineral density) with inhaled formulations, although much lower than with oral glucocorticosteroids. Systemic exposure after corticosteroids inhalation is due both to the fractions absorbed through the lungs and also to the amount which is swallowed and absorbed by the gut.
Combinations use: Instead of increasing corticosteroids doses whenever asthma control is not achieved, to obtain better efficacy and to avoid the increase of side effects risk, steroid therapy can be combined with the addition of a long-acting β2-agonist. |
