Studies suggest that N-acetylcysteine (NAC) potentially reduces inflammation and hyperinflation in patients with COPD.

In this pilot study the efficacy, safety and tolerability of high dose NAC in 12 patients with moderate COPD will be examined. These patients will receive a placebo for 12 weeks and NAC for 12 weeks in a dosage of 3 times 600 mg a day on top of their usual medication in a randomized crossover design. All subjects will be followed for 28 weeks.

The effect of high dose NAC on small airways will be assessed by measuring the total and peripheral airway resistance calculated with Computational Fluid Dynamics (CFD). The effect on oxidative stress will be assessed by measuring exhaled NO and specific markers (CRP, erythrocyte sedimentation rate, IL-6, 8-isoprostane, H2O2, TNF-alfa, glutathione, GPX, SOD and IL-8) in blood and Exhaled Breath Condensate (EBC). Dynamic and static lung volumes will be assessed by spirometry, body plethysmography and diffusion. Quality of life and symptoms will be assessed by the St George Respiratory Questionnaire.

Inclusion Criteria:

1. Patients with documented COPD based on the following criteria:

   • Smoking history of at least 10 pack-years
   • Decreased Tiffeneau index (FEV1/(FVC < 0.70)

2. Patients aged ≥ 40 years

3. Patients who stopped smoking since more than 1 month

4. Patients who present moderate COPD with an FEV1 between 50 and 80% of predicted (GOLD 2)

5. Patients should be treated according to GOLD guidelines

Exclusion Criteria:

1. Unstable patients who developed an exacerbation during the last 8 weeks
2. Patients who are current smokers or stopped less than 1 month
3. Patients who are allergic to acetylcysteine or to another element of the product
4. Patients with phenylketonuria or an untreated active peptic ulcer
5. Patients with any stage kidney and/or heart insufficiency or hypertension
6. Patients already treated with NAC for more than 6 months or during the last 3 months
7. Patients on continuous treatment with oral, inhalation, intravenous or intramuscular corticosteroids
8. Patients who are pregnant or are breast-feeding
9. Patients who are treated with orally administered cephalosporins
10. Patients using supplements containing antioxidants as vitamins C or E