NAC (N-acetylcysteine) – Clinical Summary from Sloan Kettering Memorial Cancer Center’s Integrative Medicine website

NAC (N-acetylcysteine) has been much studied as a dietary supplement, and is more widely used in Europe than in the US, especially for conditions such as chronic bronchitis or as an antidote to acetaminophen poisoning. Its usefulness for people with HIV has been investigated (sometimes contentiously) by many reseachers in the past two decades. One way to bring the discussion up to date, while also giving the broadest overview of NAC’s applications and potential applications, is to refer to the entry found on the Sloan Kettering Memorial Cancer Center’s Integrative Medicine website–an online resource well worth consulting. (Note: references for this summary are found on the SKMCC website, which is reviewed frequently–this clinical summary, accessed 1/31/2008, was updated within the last two months.)

Clinical Summary

Endogenous antioxidant and precursor to intracellular glutathione. N-acetylcysteine (NAC) is used to prevent exacerbations of chronic bronchitis, treat drug-induced hepatotoxicity, and prevent and treat conditions of oxidative stress and reduced glutathione levels, such as HIV/AIDS, cancer, and toxicity from chemo- or radiotherapy. NAC increases plasma levels of cysteine and glutathione and has antioxidant, nucleophilic, mucolytic, and possibly chemopreventative properties. Animal models suggest anti-carcinogenic, antimetastatic, and antiangiogenic activities. Oral bioavailability is low. Studies in smokers and patients with history of adenomatous colonic polyps show an inhibition of cancer biomarker development, although NAC did not inhibit formation of secondary head and neck or lung tumors in a EUROSCAN trial. 400-1200 mg/day NAC reduces the number of acute exacerbations in patients with chronic bronchopulmonary disease, but little clinical effect on lung function is seen in patients with cystic fibrosis. NAC raises GSH and cysteine levels in HIV+ patients, but shows no effect in Lou Gehrig’s disease. Human studies evaluating the role of NAC in the prevention of chemo- or radiotherapy induced toxicities are inconclusive. Gastrointestinal side effects are most often reported.

And here’s a study, limited in its goals, but with an interesting specific finding about using NAC at the start of antiretroviral treatment in HIV:
The effect of N-acetylcysteine supplementation upon viral load, CD4, CD8, total lymphocyte count and hematocrit in individuals undergoing antiretroviral treatment
Spada C, Treitinger A, Reis M, et al. Clin Chem Lab Med 2002;40:452-455.
Individuals infected with the human immunodeficiency virus (HIV-1) present with decreased CD4, a progressive increase in viral load, compromised cell immune defense, and hematologic alterations. The aim of this study was to assess the serum viral load, CD4, CD8, lymphocyte count and hematocrit at the beginning of antiretroviral therapy in individuals who were supplemented with N-acetylcysteine (NAC). Twenty volunteers participated in this double-blind, placebo-controlled 180-day study. Ten participants received 600 mg of NAC per day (NAC group) and the other ten serving as a control group received placebo. The above mentioned parameters were determined before treatment, and after 60, 120 and 180 days. In NAC-treated patients hematocrit remained stable and an increase in CD4 cell count took place earlier than that in the control group.


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