Comparison of Corticosteroids and Bronchodilators in the Treatment of Asthma

The development of antiasthma medications aims to generate long-acting, selective and easy-to-administer agents with minimal side effects. Among the medications in current use for managing asthma, bronchodilators (mainly β2-adrenoceptor agonists), corticosteroids (derivatives of cortisone) and combination therapies of corticosteroids (ICs) and β2-agonists have shown great efficacy (Barnes, 2006). However, use of such agents presents challenges such as systemic side effects associated with corticosteroids and the short duration of action noted with earlier-generation β2-adrenoceptor agonists (Barnes, 2006). The review presented in this paper aims to highlight the benefits and drawbacks associated with use of bronchodilators and corticosteroids in the management of asthma.

To identify the benefits and drawbacks of administering corticosteroids and bronchodilators to manage asthma, a search was conducted in Biomed Central, CINAHL and ScienceDirect. Keywords used included “corticosteroids”, “bronchodilators”, “asthma” and “COPD”, joined with Boolean operators to include only studies on asthma but not chronic obstructive pulmonary disease (COPD). The selection criteria excluded articles published earlier than 2005. Various studies (249) were generated – 185 in ScienceDirect, 57 in Biomed Central and 7 in CINAHL).  Out of these studies, three primary studies and three secondary studies were selected based on their relevance.

Bronchodilators, especially β2-adrenoceptor agonists have been used in managing asthma, mainly in a combination therapy with corticosteroids, due to their bronchodilator effect (Barnes, 2006). This is especially the case with the development of Long-acting β2-adrenoceptor agonists (LABA) – e.g. salmeterol and formoterol – that has alleviated challenges (e.g. frequent administration) associated with the short duration of action of their predecessors such as salbutamol (Barnes, 2006). Supplementation of corticosteroid therapy for asthma with LABA has, for instance, been shown to increase the duration of activity and improve lung function in adults (Lotvall, Langley & Woodcock, 2006) and children (Ni Chroinin, Lasserson, Greenstone & Ducharme, 2009). Although, in children, such LABA-supplementation does not have significant benefits in reducing the rates of exacerbation of asthma to levels necessitating oral administration of steroids (Ni Chroinin et al., 2009), such benefits have been realized in adults aged 16 years and above (Kuna, 2010). A challenge in the use of LABA however remains with patients developing tolerance and the possibility that chronic administration of LABA could reduce the acute response to short duration β2-agonists administered to alleviate symptoms that persist following such LABA tolerance (Haney & Hancox, 2005)

Inhaled corticosteroids (ICSs) are a common approach used to treat persistent asthma, with oral and injected corticosteroids being shunned following their implication in inducing side effects such as metabolic disturbances and osteoporosis (Barnes, 2006). Use of ICSs in managing asthma was specifically beneficial after the development of topically-active corticosteroids such as beclomethasone dipropionate and betamethasone-17-valerate (Barnes, 2006). Early treatment with such steroids has, for instance, been associated with reduced impairment and reduced risk of severe exacerbations in patients with persistent asthma (Chipps, 2009). Other benefits associated with ICSs are: lowering exercise-induced bronchoconstriction, reducing bronchial hyperresponsiveness and improving both daytime and nighttime asthma-induced symptoms (Vaessen-Verberne et al., 2010). However, corticosteroids are implicated in inducing growth retardation in children, respiratory tract infections, and common cold (Vaessen-Verberne et al., 2010; Kuna, 2010).

Bronchodilators and corticosteroids have various features that favor their administration in a combination therapy as opposed to stand-alone administration of either. Whereas bronchodilators and corticosteroids are effective in alleviating asthma due to their respective bronchodilator and anti-inflammatory effects, the potential development of tolerance to the bronchodilators and severe adverse effects of corticosteroids challenge their use as substitute treatments for persistent asthma. A combination therapy may thus be better in enhancing treatment outcomes, while reducing the adverse effects associated with chronic administration of either the bronchodilators or the corticosteroids.

References

Barnes, PJ (2006). Drugs for asthma. Bri J Pharmacol 145: s297-s303.

Chipps, BE (2009). Inhaled corticosteroid therapy for patients with persistent asthma: learnings from studies of inhaled budesonide. Allergy Asthma Proc 30: 217-228, doi: 10.2500/aap.2009.30.3201

Haney, S, Hancox, RJ (2005). Tolerance to bronchodilation during treatment with long-acting beta-agonists, a randomized controlled trial. Respir Res 6: 107, doi:10.1186/1465-9921-6-107

Kuna, P (2010). Treatment comparison of budesonide/ formoterol with salmeterol/fluticasone propionate in adults aged ≥16 years with asthma. Clin Drug Investig 30(9): 565-579.

Lotvall, J, Langley, S, Woodcock, A (2006). Inhaled steroid/long-acting β2 agonist combination products provide 24 hours improvement in lung function in adult asthmatic patients. Respir Res 7(1): 110, doi:10.1186/1465-9921-7-110

Ni Chroinin M, Lasserson TJ, Greenstone I, Ducharme FM (2009). Addition of long-acting beta-agonists to inhaled corticosteroids for chronic asthma in children. Cochrane Database of Systematic Reviews, Issue 3. Art. No.: CD007949, doi:10.1002/14651858.CD007949.

Vaessen-Verberne, AAPH, van den Berg, NJ, van Nierop, JC, Brackel, HJL, Gerrits, GPJM, Hop, WCJ, Duiverman, EJ (2010). Combination therapy salmeterol/fluticasone versus doubling dose of fluticasone in children with asthma. Am J Repir Crit Care Med 182: 1221-1227, doi:10.1164/rccm.201002-0193OC

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