Chronic inhalation of cigarette
smoke is a prominent cause of
chronic obstructive pulmonary disease (
COPD) and provides an important source of exogenous
oxidants. In addition, several inflammatory and structural cells are a source of endogenous
oxidants in the lower airways of
COPD patients, even in former smokers. This suggests that
oxidants play a key role in the pathogenesis of
COPD. This oxidative stress is counterbalanced by the protective effects of the various
endogenous antioxidant defenses of the lower airways. A large amount of data from animal models and patients with
COPD have shown that both the stable phase of the disease, and during exacerbations, have increased oxidative stress in the lower airways compared with age-matched smokers with normal lung function. Thus, counteracting the increased oxidative stress may produce clinical benefits in
COPD patients. Smoking cessation is currently the most effective treatment of
COPD patients and reduces oxidative stress in the lower airways. In addition, many drugs used to treat
COPD have some
antioxidant effects, however, it is still unclear if their clinical efficacy is related to pharmacological modulation of the
oxidant/
antioxidant balance. Several new
antioxidant compounds are in development for the treatment of
COPD.