In chronic hepatitis C, oxidative stress increases, and plasma and liver GSH concentrations decrease. Oral NAC (1800 mg/d), although having little effect alone, may enhance the response to interferon, but the studies have conflicting results. Most show no reduction in ALT levels or viral load.
According to a report in the Journal of Interferon Research (13:279-282 1993), in interferon-unresponsive patients, the addition of 600 mg tid (3 times a day) of oral N-acetyl cysteine (NAC), a glutathione precursor, resulted in a steady decrease of ALT values in all patients, with complete normalization in 41% of cases after 5-6 months of combined therapy. The authors concluded that NAC enhanced the response to interferon in chronic hepatitis C, and suggested that further studies were needed to determine whether antioxidant therapy would be useful in conjunction with interferon treatment of hepatitis C.
Studies done in 1999 on 147 patients in Spain and Italy concluded that, although the combination treatment showed slightly better results, patients with chronic HCV infection are unlikely to benefit from the addition of N-acetyl cysteine to interferon-alpha.
An Italian study published in September 2000 by S. Neri et al., on 77 patients showed that those treated with IFN alone relapsed sooner, and concluded that “the difference between the results in patients treated with interferon and N-acetyl cysteine and those on interferon alone was significant…[we] recommend wider use of this association.” (Panminerva Med 2000 Sep;42:187-92).