Oxidant/antioxidant imbalance in smokers and chronic obstructive pulmonary disease.

Oxidant/antioxidant imbalance in smokers and chronic obstructive pulmonary disease An imbalance between oxidants and antioxidants has been proposed in the pathogenesis of chronic obstructive pulmonary disease (COPD).' Although much research has focused on the protease/antiprotease theory of the pathogenesis of COPD, particularly emphysema, less attention has been paid to the role of the oxidant/antioxidant im- balance in this condition. This is surprising since cigarette smoke, which is the major risk factor for the development of COPD, contains 10'7 oxidant molecules per puff of which 1014 are oxygen free radicals.2 There is a delicate balance between the toxicity of oxidants and the protective function of the intracellular and extracellular antioxidant defence systems which is critically important for the main- tenance of normal pulmonary cellular functions.3 In this editorial we will examine the oxidant/antioxidant imbalance in smokers and patients with COPD to determine if there is enough evidence to warrant therapeutic trials with anti- oxidant therapy in patients with COPD.