Clinical trials conducted for the efficacy of antioxidants in smokers and chronic obstructive pulmonary disease(COPD)
| Trial name | Antioxidant used | Aim of study | Disease | Outcome | First author [ref.] |
| BRONCUS | NAC | Effect of NAC on FEV1 | COPD | No effect on decline in FEV1. A reduction in lung over inflation was observed in patients with severe COPD and exacerbation rate in patients who are not treated with inhaled glucocorticoids | Decramer 174, Decramer 175 |
| Systematic Cochrane review of 23 randomised controlled trails | 2 months of oral NAC therapy | Effect of NAC and antibiotics on number of days of disability | COPD | Significant reduction in days of disability (0.65 day·patient-1·month-1) and 29% reduction in exacerbations. No difference in lung function | Poole 176, Poole 177 |
| Systematic Cochrane review of randomised, controlled trials of 11 out of 39 retrieved trials | NAC | Used a validated score to evaluate the quality of each study | COPD | Nine trials showed prevention of exacerbation and five addressed improvement of symptoms compared with 34.6% of patients receiving placebo | Stey 178 |
| A meta-analysis of published trials | NAC | To assess the possible prophylactic benefit of prolonged treatment | COPD | 23% decrease in number of acute exacerbations | Grandjean 172 |
| NAC, 600 mg b.i.d for 12 months | Effect of NAC on H2O2 and TBARS in EBC | COPD | No change in TBARS reduce H2O2 levels | Kasielski 179, De Benedetto 180 | |
| MORGEN study | Diet rich in polyphenols/bioflavanoids i.e. catechin, flavonol and flavone 58 mg·day-1 | Effect on FEV1, chronic cough, breathlessness and chronic phlegm | COPD | Positively associated with decline in FEV1 and inversely associated with chronic cough and breathlessness, but not chronic phlegm | Tabak 181 |
| European countries# | Diet rich in fruits, vegetables and fish | Effect on 20-yr COPD mortality | COPD | A 24% lower COPD mortality risk | Walda 182 |
| EQUALIFE Study | Vectrine-erdosteine, thiol compound, 300 mg b.i.d. for 8 months | Effect exacerbation rate, hospitalisation, lung function and quality of life in 124 patients | COPD | Fewer exacerbations and fewer days spent in hospital. No loss of lung function and significant improvement in health-related quality of life | Moretti 183 |
#: Finnish, Italian and Dutch cohorts. Ref.: reference; BRONCUS: Bronchitis Randomised On N-acetyl-L-cysteine Cost-Utility Study; NAC: N-acetyl-L-cysteine; FEV1: forced expiratory volume in one second; H2O2: hydrogen peroxide; TBARS: thiobarbituric acid reactive substances; EBC: exhaled breath condensate.