Table 3.

Clinical Trials conducted for the efficacy of thiols in smokers and COPD subjects

SN	Name of Trial	Antioxidant used	Aim of Study	Disease	Outcome
1	BRONCUS	NAC	Effect on FEV1	COPD	No effect. A reduction in lung over inflation in patients with severe COPD without inhaled glucocorticoids
2	Systematic Cochrane review of 23 randomized controlled trials	NAC (2 months of oral therapy)	Effect of NAC and antibiotics on number of days of disability	COPD	No effect on lung function. 29% decrease in exacerbations. Good reduction in days of disabibility (0.85 days/patient/month
3	Systematic Cochrane review of randomized controlled trials of 11 out of 39 reviewed trials	NAC	Used a validated score for evaluation of quality of each study	COPD	9 trials showed prevention of exacerbations and 5 showed improvement in symptoms compared to 34.6% patients receiving placebos
4	A meta analysis of published trials	NAC (600 mg bid for 12 months)	To assess the possible prophylactic benefit of prolonged treatment Effect on H2O2 and TBARS in EBC	COPD COPD	23% decrease in acute exacerbation No change in TBARS, reduced H2O2
5	EQUALIFE studies	Vectrine-erdosteine, thiol compound, 300mg bid for months	Exacerbation rate, hospitalization, lung function and quality of life in 124 patients	COPD	Decreased exacerbations and fewer days in hospital. No loss of lung function and improvement in health-related quality of life
6	PEACE study	Carbocysteine (carbocisteine)	Effect on rate of exacerbations	COPD	Long-term (one year) use of carbocysteine (1500 mg/day) produced reduction in numbers of exacerbations in patients with COPD

BRONCUS = Bronchitis Randomized on N-acetyl-L-cysteine Cost Utility Study, FEV1 = Forced expiratory volume in 1 second, TBARS = Thiobarbituric acid reactive substances, NAC = N-acetyl-L-cysteine, EBC = Exhaled Breath Condensate.