Oral N-acetylcysteine in the treatment of Raynaud's phenomenon secondary to systemic sclerosis: a randomized, double-blind, placebo-controlled clinical trial

Objective: To evaluate the safety and efficacy of N-acetylcysteine (NAG) orally on digital microcirculation blood flow in patients with Raynaud's phenomenon (RP) secondary to systemic sclerosis (SSc). Methods: This was a randomized, double-blind, placebo-controlled trial in which 42 patients with SSc received oral NAG at a dose of 600 mg tid (21 patients, mean age 45.6 9.5 years) or placebo (21 patients, mean age 45.0 12.7 years) for four weeks. The primary endpoint was the change in cutaneous microcirculation blood flow before and after cold stimulation measured by laser Doppler imaging (LDI) at weeks 0 and 4. The frequency and severity of RP and the number of digital ulcers were also measured at weeks 0 and 4. The adverse events were recorded in the fourth week. Results: There was no significant change in digital blood flow assessed by LDI before or after cold stimulus after four weeks of NAG or placebo. Both groups showed significant improvement in the frequency and severity of RP attacks, with no difference between the two groups. At the end of the study, the placebo group had three digital ulcers, while the NAG group showed no ulcers. NAG was well tolerated and no patient discontinued the treatment. Conclusions: NAG orally at a dose of 1800 mg/day showed no vasodilator effect on hands' microcirculation after four weeks of treatment in patients with RP secondary to SSc. (c) 2014 Elsevier Editora Ltda. All rights reserved.