Research from an international, collaborative group of scientists, led by researchers at Vanderbilt University in Tennessee, supports the safety of pirfenidone as a therapy for idiopathic pulmonary fibrosis (IPF).

The report, “Safety of pirfenidone in patients with idiopathic pulmonary fibrosis: integrated analysis of cumulative data from 5 clinical trials,“ appeared in the journal BMJ Open Respiratory Research.

IPF refers to the thickening and scarring of lung tissue; it’s not known what causes the condition.The disease results in difficulty breathing and is eventually fatal. Patients with IPF would greatly benefit from new, effective, and safe treatments for the condition.

Pirfenidone is a medication that prevents fibrosis and restores lung function in people with IPF. Three previous phase 3 clinical trials showed that pirfenidone was effective at increasing lung function, measured by a standard method called forced vital capacity (a measurement of how well the lungs work based on how much air a person can exhale with force). Pirfenidone acts by blocking molecules that increase fibrosis, namely growth factors and procollagens I.

The research team, led by Lisa Lancaster of the Department of Medicine at Vanderbilt University Medical Center, analyzed safety data from five clinical trials designed to study the use of pirfenidone in people with IPF.

Study participants included 1,299 patients treated with pirfenidone in three Phase 3 clinical trials, including the CAPACITY studies 004 and 006, and the ASCEND study 016, and two open-label studies, the RECAP study 002 and 012. Open label means that the individuals participating in the study knew information about the drug they were receiving. Researchers assessed the drug’ safety profile in these studies, starting from the first dose of pirfenidone until 28 days following the last study dose. The average time taking the medication was 1.7 years.

Pirfenidone was found to be generally safe and well-tolerated, with gastrointestinal problems and rash being the most common reported adverse events. In their article, the researchers noted “Gastrointestinal events (nausea (37.6 percent), diarrhea (28.1 percent), dyspepsia (18.4 percent), vomiting (15.9 percent)) and rash (25.0 percent) were the most common adverse events; these were generally mild to moderate in severity and without significant clinical consequence.

Elevations in alanine aminotransferase or aspartate aminotransferase greater than three times the upper limit of normal occurred in 40 of the 1,299 (3.1 percent) patients … Elevations were generally transient and reversible with dose modification or discontinuation.”

This large, comprehensive safety study supports the use of pirfenidone for IPF treatment and the prevention of lung scarring.

The U.S. FDA approved pirfenidone (Esbriet) in October 2014 based on the positive results from the ASCEND and CAPACITY clinical trials. The medication is currently produced and marketed by the biotechnology company Genentech.