Pharmacotherapy for Exercise-induced Asthma: Allowing Normal Levels of Activity and Sport

Kenneth D Fitch

Disclosures

Expert Rev Clin Pharmacol. 2010;3(1):139-152. 

In This Article

Abstract and Introduction

Abstract

Exercise-induced bronchoconstriction (EIB) is experienced by the majority of an estimated 300 million individuals who have asthma, a condition that affects all ages and is increasing globally. Respiratory water loss with dehydration of the airways causing mediator release and airway narrowing is considered the cause of EIB, the severity of which will be increased if the inhaled air is cold or polluted. Adequate control of asthma is essential to minimize or prevent EIB and permit normal levels of physical activity and sport. This is important because exercise is a necessary component of daily living, assists in obtaining and maintaining a healthy body and has been demonstrated to benefit asthmatics. Inhaled glucocorticosteroids and inhaled β2-adrenoceptor agonists (IβA) are the pharmacological agents of choice to manage asthma and minimize EIB, assisted when necessary, by other drugs including leukotriene receptor antagonists and chromones. Tolerance from daily use of IβA is of concern and more flexible drug therapy needs to be considered. Optimal use of inhalers to deliver drugs effectively requires closer attention. Pharmacogenetics may hold the key to future drug therapy.

Introduction

Exercise has a paradoxical, even a perverse relationship to asthma. For more than 1800 years, exercise has been known to provoke asthma[1] and despite this, exercise is an accepted therapeutic modality to assist asthma. One of the first recorded instances of prescribed exercise that benefitted an asthmatic was for the Archbishop of Edinburgh more than 450 years ago.[2] Exercise-induced asthma (EIA) is the transient bronchoconstriction induced during or but mostly after exercise. Although some authorities restrict the term exercise-induced bronchoconstriction (EIB) to a small minority who develop bronchoconstriction solely with exercise,[3] this review will use the term EIB throughout, as it is self explanatory.

As the vast majority of asthmatics experience bronchoconstriction when exercising, many have tended to avoid exercise, and it was only 50 years ago that exercise programs began to be developed to assist asthmatics, predominantly children[4] in the USA and less than 40 years since the first studies to scientifically evaluate intensive exercise programs for asthmatics were undertaken.[5] This was the period when a range of inhaled medications became available, notably the chromones, inhaled selective β2-adrenoceptor agonists (IβA) and inhaled corticosteroids (ICS) in that order, to pharmacologically prevent or minimize EIB, assisting asthmatics to exercise across a range of physical activities and sports. Physical and psychological benefits have followed as well as some outstanding sporting successes.[6] By contrast, during the past decade, evidence is accumulating that many years of intensive endurance exercise training may be provoking asthma and/or airway hyperresponsiveness (AHR) in elite athletes.[7]

For individuals with asthma to be able to undertake normal levels of activity it is necessary to managing asthma appropriately and to minimize or prevent EIB. This review explores the pathophysiology of EIB, the apparent enigmas in the relationship between exercise and asthma and, in more depth, the roles of the steadily increasing range of pharmacological agents available to assist asthmatics to normalize their physical activity and sport.

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