“The use of N-acetylcysteine significantly reduces the odds of exacerbation in patients with COPD, an effect possibly attenuated by inhaled steroids but not smoking.”
“Treatment effect was not reduced in studies which enrolled > 50% active smokers (odds ratio = 0.36 [0.24–0.55], p < 0.001), … observed with exclusion of subjects using concurrent inhaled corticosteroids (odds ratio = 0.42 [0.32–0.54], p < 0.0001), suggesting that inhaled steroids … N-acetylcysteine.”