Administration of N-acetylcysteine and Vitamin C to augment antioxidant protection in patients with chronic bronchitis.

摘要

Summary. BACKGROUND AND OBJECTIVE: N-acetylcysteine (NAC) is known to have direct antioxidant properties due to its thiole-group on the one hand as well as indirect antioxidant capacity as cysteine-donor to cellular glutathione-synthesis on the other hand. Therefore NAC appears to be attractive in antioxidant therapy of inflammatory disorders of the lung. This study aimed to investigate the use of antioxidant therapy with NAC in chronic bronchitis. PATIENTS AND METHODS: In this randomized, double-blinded and placebo-controlled trial100 patients divided into four groups were observed over a period of 3 months. The treatment consistet of either 600 mg NAC bid, 500 mg Vitamin C bid, a combination of those two substances using the same dosage or a placebo-preparation. The release of reactive oxygen species from isolated neutrophilic granulocytes and mononuclear cells was quantified before treatment and after three months using chemiluminescence (primary outcome parameter). Furthermore cellular glutathione content of these inflammatory cells was quantified spectrometrically. In addition, leukocyte-count and erythrocyte sedimentation rate as well as spirometry and a standardized symptom-based questionnaire were used to monitor the clinical efficacy. RESULTS: None of the above substances were able to significantly reduce the release of reactive oxygen species from the examined population of inflammatory cells. They also failed to increase intracellular glutathione-levels. Concordantly, no changes in spirometry and the results of the symptom-based questionnaire were found. CONCLUSION: In summary NAC, Vitamin C and the NAC/ Vitamin C-combination did neither enhance antioxidant protection in the blood nor is it of any clinical benefit in chronic bronchitis. Possible reasons may be a lack of antioxidant defficiency in these patients and negative feedback mechanisms of the glutathione-system.