Long-term treatment with oral N-acetylcysteine: Affects lung function but not sputum inflammation in cystic fibrosis subjects. A phase II randomized placebo-controlled trial

PurposeTo evaluate the effects of oral N-acetylcysteine (NAC), which replenishes systemic glutathione, on decreasing inflammation and improving lung function in CF airways.MethodsA multicenter, randomized, double-blind proof of concept study in which 70 CF subjects received NAC or placebo orally thrice daily for 24 weeks. Endpoints: primary, change in sputum human neutrophil elastase (HNE) activity; secondary, FEV1 and other clinical lung function measures; and safety, the safety and tolerability of NAC and the potential of NAC to promote pulmonary hypertension in subjects with CF.ResultsLung function (FEV1 and FEF25-75%) remained stable or increased slightly in the NAC group but decreased in the placebo group (p = 0.02 and 0.02). Log10 HNE activity remained equal between cohorts (difference 0.21, 95% CI − 0.07 to 0.48, p = 0.14).ConclusionsNAC recipients maintained their lung function while placebo recipients declined (24 week FEV1 treatment effect = 150 mL, p < 0.02). However no effect on HNE activity and other selected biomarkers of neutrophilic inflammation were detected. Further studies on mechanism and clinical outcomes are warranted.