Long-term macrolide treatment for chronic respiratory disease.

Long-term macrolide treatment was first shown to alter the natural history of diffuse panbronchiolitis (DPB) in the late 1980s. Since then, macrolides have been demonstrated to exert anti-inflammatory and immunomodulatory activity in addition to being antimicrobial. Indeed, their spectrum of action extends to the regulation of leukocyte function and production of inflammatory mediators, control of mucus hypersecretion, resolution of inflammation and modulation of host defence mechanisms. As such, the potential benefit of macrolide antibiotics has been evaluated in a variety of chronic respiratory diseases. The best studied condition is cystic fibrosis, of which there have been six randomised controlled trials showing evidence of benefit. However, most of the studies were limited by small numbers of patients and short follow-up. More recently, landmark studies have demonstrated the efficacy of azithromycin in reducing the risk of acute exacerbations in patients with chronic obstructive pulmonary disease, but the optimal duration and dosing of macrolide treatment remain uncertain. With the exception of patients with DPB and cystic fibrosis, until clear evidence of efficacy is available, the long-term use of macrolides should be limited to highly selected patients after careful evaluation of benefit and harm, or in the context of randomised controlled clinical trials.