Impact of add-on pranlukast in stable asthma; the additive effect on peripheral airway inflammation.
BACKGROUND
The importance of airway inflammation has been highlighted in the pathophysiology of asthma. Even in controlled asthmatics treated with inhaled corticosteroid (ICS), residual airway inflammation is reported. Systemic therapy with oral leukotriene receptor antagonist, pranlukast, may have additive effects to improve asthma control.


METHODS
Twenty-five controlled asthmatics treated with ICS or ICS plus long-acting β2-agonist (LABA) were enrolled for a randomized crossover trial evaluating the effect of additional oral pranlukast. The patients were assigned to two groups receiving ICS (+LABA) or ICS (+LABA) + pranlukast for 8 weeks. After washout period, two groups were switched over for another 8 weeks. Fraction of exhaled nitric oxide (FeNO), lung function tests, peak expiratory flow (PEF) and asthma control test (ACT) were evaluated at the beginning and end of each period. Central airway NO flux (J'(awNO)) and peripheral airway/alveolar NO concentration (C(ANO)) were measured and adjusted for axial NO back-diffusion.


RESULTS
FEV1, % predicted, forced expired flow (FEF) (25-75), % predicted, morning PEF and ACT were significantly increased after the addition of pranlukast. Oral pranlukast administration significantly decreased both C(ANO) and corrected C(ANO).


CONCLUSIONS
The addition of oral pranlukast to ICS or ICS + LABA therapy may improve asthma control with reducing distal airway inflammation.


TRIAL REGISTRATION
UMIN 000003781.