Clarithromycin suppresses bronchial hyperresponsiveness associated with eosinophilic inflammation in patients with asthma

Background: Although long-term administration of 14-membered macrolide anti biotics is a therapeutic alternative in asthma, both its pharmacologic mech anism of action and association with the pathogenesis of asthma remain obsc ure. Objective: This study investigated the suppressive effect of clarithromycin on airway responsiveness to methacholine provocation testing and examined whether chrarithromycin's antiasthmatic activity is associated with a reduc tion in eosinophilic inflammation. Methods: For 8 weeks, patients received 200 mg of clarithromycin or identic al-appearing placebo twice daily. We assessed the effects of treatment with clarithromycin on bronchoconstriction precipitated by inhalation of methac holine in 17 adults with mild or moderate bronchial asthma who were in stab le clinical condition. A double-blind, randomized, crossover design was use d. Eosinophil counts and eosinophilic cationic protein (ECP) levels were de termined in brood and sputum samples obtained on the morning of the methach oline provocation testing day. Results: After 8 weeks of treatment with clarithromycin, patients' symptoms , blood and sputum eosinophils counts and sputum ECP levels were significan tly decreased compared with both placebo and baseline. Furthermore, values of PC, methacholine improved in all patients after clarithromycin treatment . Conclusions: Clarithromycin has a bronchial anti-inflammatory effect associ ated with decreased eosinophilic infiltration. This study suggests interest ing therapeutic possibilities for bronchial asthma that warrant further tri als.