Table 3.

The clinical studies on the efficacy of carbocysteine in COPD.

Antioxidant	Study Design	Duration	Study Outcomes	References
Carbocysteine	Double-blind, randomized, placebo-controlled study	12 months	Prolonged (12 months) treatment with carbocysteine decreased the exacerbations in COPD patients, reduced exacerbations, no loss of lung activity, ameliorated health-related quality of life.	[187,192]
Carbocysteine	Multicenter, placebo-controlled, double-blind, parallel group trial	6 months	Duration of the acute respiratory illness was markedly decreased and this was linked with a marked decrease in the administration of antibiotics during the trial period, no serious adverse effects were observed.	[193]
Carbocysteine	Randomized controlled trial	12 months	Consistently decreased the frequency of exacerbations, did not alter the lung function.	[188]
Carbocysteine	Double-blind controlled study	3 months	Improved the capacity to cough up bronchial secretions, markedly elevated the sputum volume output, ameliorated ventilation.	[194]
Carbocysteine	Single-blind study	8 weeks	Greatly eased expectoration, increased the level of expectorated sputum, markedly increased peak expiratory flow rate, ameliorated the severity of dyspnea.	[195]
Carbocysteine	Randomized controlled trial	12 months	Markedly decreased the exacerbation rate and commoncolds, no substantial differences in the extent of COPD.	[196,197]