Abstract
AimsCough is a common symptom of bronchial asthma, a chronic inflammatory airway disease. Recently, the therapeutic effects of selective phosphodiesterase (PDE) inhibitors have been focused on bronchial asthma. This study was designed to investigate the clinical effect of PDE 3 inhibition on cough reflex sensitivity in elderly patients with bronchial asthma.MethodsEffects of cilostazol, a PDE 3 inhibitor, on cough response to inhaled capsaicin were examined in 11 patients over 70 years with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity.ResultsThe cough threshold was significantly (p < 0.05) increased after two-week treatment with cilostazol (100 mg twice a day orally) compared with placebo [48.8 (GSEM 1.4) vs. 29.2 (GSEM 1.3) μM].ConclusionThese findings indicate that PDE 3 inhibition may be a novel therapeutic option for elderly patients with asthma, especially for their cough symptoms.
Highlights
Chronic cough is a frequent problem in general practice and one of the commonest reasons for referral to respiratory clinic
We have demonstrated that a phosphodiesterase 3 inhibitor, cilostazol, reduces bronchial hyperresponsiveness to inhaled methacholine in elderly patients with stable asthma [10]
Cough threshold to inhaled capsaicin before each treatment and after treatment with cilostazol and placebo are shown in figure 1
Summary
Chronic cough is a frequent problem in general practice and one of the commonest reasons for referral to respiratory clinic. A patient's quality of life becomes severely affected through loss of sleep, interruption of work and social embarrassment. Every effort should be made to clarify the cause of cough because specific therapy has a higher likelihood of success than empirical therapy. A previous study revealed that patients with persistent cough had three times the risk of developing chronic wheezing as compared to normal subjects [2]. It is important to disclose the mechanism of persistent cough and to develop more efficacious treatment. Though cough has been considered to result from stimulation of airway sensory nerve endings within the respiratory tract [1], the potential mechanism by which the cough reflex may be altered in humans remains obscure
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