Regular treatment with β2-agonists has been reported to be associated with an increase in risk of asthma death or near death, and with a deterioration in asthma symptom control. Low-dose β2-agonists provide effective bronchodilatation and bronchoprotection, even though maximal bronchodilatation is not achieved, and they may offer a better safety profile. In a double-blind, randomized, cross-over study, we evaluated the efficacy of low-dose salbutamol metered-dose inhaler (50 μg · puff-1), used over a period of 2 weeks, compared with a standard dose (100 μg · puff-1) in control of asthma symptoms in 20 moderately severe asthmatic subjects using inhaled glucocorticosteroid therapy. Asthma control was assessed by symptom scores, peak flow rates, spirometry, inhaler usage and, where possible, by bronchial responsiveness to methacholine. Despite a 46% reduction in mean weekly salbutamol dosage, mean forced expiratory volume in one second (FEV1), morning and evening peak expiratory flow (PEF), PEF variability, dose of methacholine provoking a 20% decrease in FEV1 (PC20) (n = 9), and symptom scores showed no difference between low-dose and standard inhaler treatment periods. Low-dose inhaler administration resulted in a small but significant increase in number of inhaler actuations. Low-dose salbutamol metered-dose inhaler may, thus, be useful for control of symptoms in moderately severe asthma This strategy could be used to achieve a reduction in total β2-agonist usage, which may minimize any potential for adverse effects.
- β-Agonist tolerance
- Dose reduction