A double-blind, cross-over, study of oral N-acetylcysteine in Sjögren's syndrome.

Twenty-six patients with primary or secondary Sjögren's syndrome were treated in a double-blind, cross-over trial for a four week period with oral N-Acetylcysteine and placebo. Before treatment there were significantly elevated salivary lactoferrin levels in the patients when compared to 51 healthy controls (p = 0.0005), and significantly decreased levels of tear lysozyme when compared to 24 controls (p = 0.0003). Salivary sodium, potassium, inorganic phosphate, amylase and immunoglobulin G, A or M levels were not significantly different from control values. After treatment with N-Acetylcysteine, Sjögren's syndrome patients reported improvements in ocular soreness (p = 0.004), ocular irritability (p = 0.006), halitosis (p = 0.033) and daytime thirst (p = 0.033). N-Acetylcysteine, but not placebo improved the van Bijsterveld score (p = 0.026), but neither agent improved the Schirmer test, the tear break up time or any of the laboratory tests. These results suggest that N-Acetylcysteine may have a true therapeutic effect on the ocular symptoms of Sjögren's syndrome and be worthy of a longer study.