NIH Finds NAC Ineffective In Idiopathic Pulmonary Fibrosis

The National Institutes of Health (NIH) reports in a press release that a common treatment for patients with idiopathic pulmonary fibrosis (IPF) is no better than a placebo. A therapy that combines N-acetylcysteine (NAC) with immunosuppressive and anti-inflammatory drugs does not preserve lung function in people with the

chronic, progressive lung disease. Investigators have published their findings in the May 24, 2014 edition of the New England Journal of Medicine.

James Kiley, Ph.D., director of the Division of Lung Diseases at the NIH’s National Heart, Lung, and Blood Institute (NHLBI), said, “While it is disappointing that NAC was ineffective in preserving lung function in IPF, these are the kind of high-quality data that patients and their caregivers need to make informed decisions.”

NAC Treatment

N-acetylcysteine (NAC) is derived from the amino acid L-cysteine, a protein building block. NAC is used for various medical purposes including acetaminophen and carbon monoxide poisoning, unstable angina, chronic bronchitis, alcoholic liver damage, and pneumonia. It has antioxidant properties and has been used to preserve lung function in patients with mild to moderate lung damage from the disease idiopathic pulmonary fibrosis (IPF). 

NAC Clinical Trial

The NAC treatment combined with anti-inflammatory and immunosuppressive drugs has been a standard and common treatment due to findings from previous studies. NIH investigators conducted a new trial and titled their report, “Prednisone, Azathioprine, and N-Acetylcysteine: A Study That Evaluates Response in Idiopathic Pulmonary Fibrosis (PANTHER-IPF).” The study evaluated N-acetylcysteine (NAC) along with prednisone and azathioprine.

Investigators assigned patients to one of three groups. One group received a combination of prednisone, azathioprine, and NAC. One group received NAC alone and one group received a placebo. The NIH stopped the combination therapy group in 2011 due to concerns about safety because interim results showed no difference in lung function and increased hospitalization and death.

The NAC monotherapy and the placebo group continued. The primary measurement was the change in longitudinal measurements of forced vital capacity (FVC) during a 60-week treatment period. FVC is a measurement of the total amount of air a person exhales after taking the deepest breath possible. Results showed no statistically significant differences between patients in the NAC group and the placebo group. Findings held for FVC declines, IPF symptom flare-ups, hospitalizations, and deaths.