N-acetylcysteine for Primary Sjögren's Syndrome

N-acetylcysteine (NAC) allows the elimination of reactive oxygen species (ROSs) and it has an anti-inflammatory effect. For this reason, NAC has been used and researched for treatment of several diseases, such as autoimmune diseases. In these diseases there are a process of oxidative stress due to chronic inflammation, which promotes an imbalance between ROSs levels and the cellular capacity to eliminate reactive intermediates and repair the resulting damage through antioxidants. The imbalance between the production of free radicals from oxygen and antioxidant species may also be involved in the pathogenesis of primary Sjögren's syndrome (pSS). In fact, increased levels of oxidative stress markers were detected in biopsy samples from minor salivary glands in these patients. Treatment of pSS is not well established and it is also not able to modify the evolution of the disease, being often only symptomatic. In addition, there is little data in the literature regarding the true efficacy of NAC in the treatment of pSS and the few existing studies have evaluated heterogeneous populations (including patients with other causes of sicca syndrome) and validated instruments to measure the symptom index and disease activity were not use in these previous studies. Thus, the present randomized double-blind clinical study aims to evaluate the efficacy of NAC in the control of sicca syndrome symptoms in a homogeneous population of patients with pSS (not only regarding the classification criteria, but also regarding the low rate of systemic disease activity at study inclusion) through tests widely accepted in the literature. Additionally, the investigators will study the possible role of NAC on oxidative stress in peripheral blood and saliva of these patients.