Table 1—

Clinical trials conducted for the efficacy of antioxidants in smokers and chronic obstructive pulmonary disease(COPD)

Trial nameAntioxidant usedAim of studyDiseaseOutcomeFirst author [ref.]
BRONCUSNACEffect of NAC on FEV1COPDNo 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 glucocorticoidsDecramer 174, Decramer 175
Systematic Cochrane review of 23 randomised controlled trails2 months of oral NAC therapyEffect of NAC and antibiotics on number of days of disabilityCOPDSignificant reduction in days of disability (0.65 day·patient-1·month-1) and 29% reduction in exacerbations. No difference in lung functionPoole 176, Poole 177
Systematic Cochrane review of randomised, controlled trials of 11 out of 39 retrieved trialsNACUsed a validated score to evaluate the quality of each studyCOPDNine trials showed prevention of exacerbation and five addressed improvement of symptoms compared with 34.6% of patients receiving placeboStey 178
A meta-analysis of published trialsNACTo assess the possible prophylactic benefit of prolonged treatmentCOPD23% decrease in number of acute exacerbationsGrandjean 172
NAC, 600 mg b.i.d for 12 monthsEffect of NAC on H2O2 and TBARS in EBCCOPDNo change in TBARS reduce H2O2 levelsKasielski 179, De Benedetto 180
MORGEN studyDiet rich in polyphenols/bioflavanoids i.e. catechin, flavonol and flavone 58 mg·day-1Effect on FEV1, chronic cough, breathlessness and chronic phlegmCOPDPositively associated with decline in FEV1 and inversely associated with chronic cough and breathlessness, but not chronic phlegmTabak 181
European countries#Diet rich in fruits, vegetables and fishEffect on 20-yr COPD mortalityCOPDA 24% lower COPD mortality riskWalda 182
EQUALIFE StudyVectrine-erdosteine, thiol compound, 300 mg b.i.d. for 8 monthsEffect exacerbation rate, hospitalisation, lung function and quality of life in 124 patientsCOPDFewer exacerbations and fewer days spent in hospital. No loss of lung function and significant improvement in health-related quality of lifeMoretti 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.