What is the optimal dose of N-acetylcysteine in adult patients with bronchiectasis?-data from the RIBRON registry.

Background: Bronchiectasis is characterized by excessive respiratory secretions, the management of which is clinically significant. Among the available pharmacological treatments, mucolytics play a pivotal role. N-acetylcysteine (N-AC) is the most commonly used mucolytic; however, the optimal dosing regimen remains inadequately defined. The primary aim of the present study is to specifically evaluate the efficacy of 1,200 mg/day of N-AC compared to 600 mg/day in patients with bronchiectasis. Methods: This was a retrospective, longitudinal, observational, multi-center study conducted across 43 centers, involving a cohort of 2,461 adult patients diagnosed with bronchiectasis based on a stable clinical state receiving either 600 mg/day of N-AC (n=252) or 1,200 mg/day (n=116), and provided follow-up data were available for 2 years. Propensity score matching (PSM) was employed to balance baseline characteristics between groups. Final outcomes were further adjusted for additional clinically relevant variables. Intergroup differences in intra-group changes were analyzed using a Poisson test. Results: Following PSM, the 1,200 mg/day N-AC group (n=104) demonstrated a statistically significant, fully adjusted reduction in exacerbations (-48.6%, P=0.01), hospitalizations (-29.9%, P=0.038), and total exacerbation rates (-54.1%, P=0.002), compared to the 600 mg/day group (n=219). Furthermore, the proportion of patients with more than 20 cc/day of sputum volume and those with mucopurulent sputum decreased by 24.3% (P=0.001) and 8.5% (P=0.041), respectively, in the 1,200 mg/day group versus the 600 mg/day group. No statistically significant difference was observed in the rate of Conclusions: N-AC at a dose of 1,200 mg/day is more effective than 600 mg/day in reducing exacerbations, hospitalizations, and daily sputum volume in patients with bronchiectasis.