How Does N-acetyl-l-cysteine Help With Pulmonary Fibrosis?

Idiopathic pulmonary fibrosis is a chronic and ultimately fatal lung disease diagnosed in about 30,000 Americans each year. "Idiopathic" refers to the fact that there is no known cause in most cases. It occurs mostly in middle-aged and older adults, with an average survival time of three to five years, according to the National Institutes of Health. Over time, the lung tissue becomes thickened, stiff and scarred, losing its ability to transfer oxygen into the bloodstream. There is currently no cure or FDA-approved treatment for pulmonary fibrosis, but a variety of therapies have been used to help manage the condition, including N-acetyl-L-cysteine.

Possible Causes

The cause of idiopathic pulmonary fibrosis is not known, but as of early 2011, researchers believed that there is an abnormal inflammatory and fibrotic response to injury in the lining of the tiny air sacs in the lungs known as alveoli. This results in alveolar scarring and thickening, and the reduced ability to move oxygen into the bloodstream. According to a report in the "New England Journal of Medicine," an oxidant-antioxidant imbalance may contribute to the repeated injury to the lung lining. Cigarette smoking, prolonged exposure to occupational or environmental contaminants, lung infections, certain medicines, and acid reflux disease may increase risk for idiopathic pulmonary fibrosis.

How N-Acetyl-L-Cysteine Works

N-acetyl-L-cysteine is a naturally occurring antioxidant. It is a precursor of glutathione, a major antioxidant in the body that is thought to be reduced in the lungs of patients with idiopathic pulmonary fibrosis. Several studies, including two published in the "American Journal of Respiratory Critical Care Medicine," have shown that N-acetyl-L-cysteine taken orally or intravenously can restore depleted levels of glutathione in the lungs. Researchers think that N-acetyl-L-cysteine may prevent some of the oxidative injury to lung tissue that precedes the proliferation of fibrosis and scarring, according to the Pulmonary Fibrosis Foundation.

Evidence

In a study published in the "New England Journal of Medicine," Dr. Maurits Demedts of University Hospital in Belgium studied the effectiveness of a high dose of N-acetyl-L-cysteine taken by mouth for one year on idiopathic pulmonary fibrosis in 155 patients. Either N-acetyl-L-cysteine or a placebo was added to anti-inflammatory therapy with azathioprine and prednisone, which is currently standard treatment according to the International Idiopathic Pulmonary Fibrosis Consensus Statement. Compared with a placebo, N-acetyl-l-cysteine slowed the deterioration of lung function by 9 percent based on surrogate measures of respiratory muscle strength and by 24 percent based on a surrogate measure of the capacity of the lung to transfer gases. Patients with less progressed disease at the start of treatment responded better to therapy. Other ongoing studies are investigating the effectiveness of N-acetyl-L-cysteine in combination with other drugs, according to the Pulmonary Fibrosis Foundation.

Other Treatment Options

Cyclophosphamide is an anticancer drug with immunosuppressive properties that is sometimes given with prednisone in an attempt to treat symptoms. Some patients require supplemental oxygen, which can reduce breathlessness and help patients be more active. Lung transplantation is currently the most viable course of treatment to extend the lives of those with idiopathic pulmonary fibrosis, according to the Pulmonary Fibrosis Foundation, and should be discussed with your physician as soon as you are diagnosed. Because there are currently no FDA-approved therapies, many patients choose to participate in clinical trials of experimental therapies. Patients should discuss this possibility with their physician at the time of diagnosis.