WEDNESDAY, Nov. 23 (HealthDay News) -- Adding a high-dose antioxidant to standard drug therapy can improve lung function for patients with a serious respiratory disease called idiopathic pulmonary fibrosis.
Pulmonary fibrosis is a chronic and often fatal disease characterized by extra scar tissue in the lungs. The disease affects some 80,000 people in the United States and is treated with steroids and other immunosuppressive therapies. However, use of these drugs tends to have little effect and about 70 percent of people die within five years of diagnosis.
The report, which appears in the November 24 issue of The New England Journal of Medicine, found that patients' lung function improved when high-doses of the enzyme N-acetylcysteine were added to standard drug treatment.
Acetylcysteine is an enzyme that acts as an antioxidant and is also used to help loosen up mucus.
"Up to now, there are no real effective drugs for idiopathic pulmonary fibrosis (IPF), which is a disease with a poor prognosis," said lead author Dr. Maurits Demedts, from the Division of Pneumology at University Hospital Gasthuisberg, Leuven, Belgium.
"Our study showed that adding high oral doses of N-acetylcysteine to the standard [drug] therapy of prednisone and azathioprine -- which, however, by most experts is considered to be probably of no real effectiveness -- significantly slows the rate of deterioration of the lung function," he said.
In their study, Demedts' team randomly assigned 182 patients to receive 600 milligrams of N- acetylcysteine three times a day or a placebo plus standard drug therapy.
The researchers found that, compared with placebo, N-acetylcysteine slowed the deterioration of vital lung capacity by nine percent and diffusing capacity by 24 percent after one year.
During the trial, nine percent of the patients receiving N-acetylcysteine died, as did 11 percent of the patients receiving placebo, the researchers report.
"We consider these effects of adding N-acetylcysteine to the standard therapy clinically relevant, because it is accepted from other recent studies that decreases of at least 10 percent for vital capacity and 15 percent for diffusing capacity over a period of six to 12 months are associated with an increased risk of death in IPF," Demedts said.
Demedts believes that this treatment can be effective in boosting IPF treatment. "High-dose N-acetylcysteine in addition to standard therapy is a rational treatment option for patients with IPF," he said.
One expert thinks that claims for increased survival of IPF patients taking N-acetylcysteine cannot be substantiated based on this study alone.
"They [the researchers] infer that the effect is sufficient to translate into prolongation of life, but we cannot be certain of this," said Dr. Norman H. Edelman, chief medical officer at the American Lung Association.
"IPF remains a troublesome disease for relatively young and old alike. It is usually relentlessly progressive with little impact being made by current therapy. The younger patients end up getting lung transplants if they are lucky," he said.
Another expert said the benefits of N-acetylcysteine, if any, can't be shown from this study, since patients were taking other medications, so the effect of N-acetylcysteine was masked.
"Because of the design of the study, we can't know if N-acetylcysteine independently is beneficial for patients with IPF," said Dr. Gary W. Hunninghake, a professor of internal medicine and director of the Pulmonary Program in Internal Medicine at the University of Iowa, and author of an accompanying journal editorial.
"There are two possibilities," Hunninghake said. "One is that N-acetylcysteine truly helps patients with IPF. The other possibility is that its main effect was to ameliorate the toxicity of azathioprine," he added.
Although prednisone and azathioprine are commonly used to treat IPF, there is little evidence that they help patients with the disease, and in fact they may be toxic, Hunninghake added.
Hunninghake believes that N-acetylcysteine might be potentially useful in treating IPF. "I am not dismissing that," he said. "But you just can't tell from this study."
As for patients, Hunninghake thinks that taking N-acetylcysteine won't do any harm. It will almost certainly do no harm, and it may be of value," he said. "We just don't know."
More information
The National Library of Medicine can tell you more about pulmonary fibrosis.
