RESUMO
OBJECTIVE: Acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) accelerate the progressive impairment of lung function and general health. Together with maintenance therapy for chronic obstructive pulmonary disease (COPD), N-acetylcysteine (NAC) and natural propolis have demonstrated pharmacological properties that address crucial pathophysiological processes underlying COPD and may prevent AECOPDs. This study aims at responding to dose-dependent efficacy and safety concerns regarding a propolis-NAC combination for the reduction of COPD exacerbation rates. PATIENTS AND METHODS: This was a single-center, randomized, double-blind, phase IV trial with three treatment arms: Placebo and two active substance groups, one (AS-600) received 600 mg of NAC + 80 mg of propolis while the other (AS-1,200) received 1,200 mg of NAC + 160 mg of propolis. Following an AECOPD, frequent-exacerbation phenotype patients (n=46) were assigned a once-daily three-month therapy with the study drug and one year follow-up. The primary endpoint was the COPD exacerbation incidence rate during the follow-up period as a measure of dose-dependent efficacy of NAC-propolis combination compared to placebo. RESULTS: There was a statistically significant difference in the AECOPD incidence rate: 52.6% in patients that received placebo, 15.4% that received AS-600 and only 7.1% that received AS-1,200 (Fisher's exact test, p = 0.013). Compared to placebo, AECOPD frequency was significantly lower only in AS-1,200 (p=0.009). Compared to placebo, the relative risk for exacerbation was 0.29 in AS-600 and 0.13 in AS-1,200. No adverse events related to the treatment were reported. CONCLUSIONS: Oral combination of natural propolis with NAC confirmed formulation efficiency with a favorable safety profile. Our results need to be confirmed by larger clinical trials.