Background A randomised controlled trial in Japan showed that inhaled N-acetylcysteine monotherapy stabilised serial decline in forced vital capacity (FVC) in some patients with early idiopathic pulmonary fibrosis (IPF). However, the efficacy and tolerability of combination therapy with an antifibrotic agent and inhaled N-acetylcysteine are unknown.
Methods This 48-week, randomised, open-label, multicentre phase 3 trial compared the efficacy and tolerability of combination therapy with pirfenidone plus inhaled N-acetylcysteine 352.4 mg twice daily with the results for pirfenidone alone in patients with IPF. The primary end-point was annual rate of decline in FVC. Exploratory efficacy measurements included serial change in diffusing capacity of the lung for carbon monoxide (DLCO) and 6-min walk distance (6MWD), progression-free survival (PFS), incidence of acute exacerbation, and tolerability.