Efficacy and effects of Pirfenidone

Pirfenidone was more effective than placebo, a dummy treatment, at slowing the worsening of lung function in two major studies involving779 patients with idiopathic pulmonary fibrosis (IPF). The first study compared two doses of pirfenidone (399 mg and 801 mg three times a day). The primary measure of efficacy was changes in patients' lung function after 72 weeks of treatment, as measured by their "forced vital capacity" (FVC). FVC is the maximum amount of air a patient can forcefully exhale after taking a deep breath, and decreases as the condition worsens.

In the first study, patients taking pirfenidone had a smaller decrease in FVC after 72 weeksthan those taking placebo. The first study also found that pirfenidone was most effective at higher doses. The higher-dose results from the first study, combined with the results from the second study (involving the same higher dose), showed that patients taking pirfenidone experienced an average 8.5% reduction in FVC.

Analysis of data from these two studies, as well as from a third study, looked at the role of pirfenidone indifferent stages of IPF (advanced and non-advanced disease). Patients are classified as having advanced IPF if their FVC is less than 50 percent and/or the lung's carbon monoxide diffusing capacity (a measure of the lung's ability to transfer gas from inhaled air to the blood) is less than 35 percent. These analyzes included 170 patients with advanced and 1077 patients with non-advanced IPF, respectively. Pirfenidone was more effective than placebo in slowing the deterioration of lung function in patients with advanced and non-advanced IPF. After 52 weeks of treatment, FVC decreased by 46% (151 mL) in patients with advanced IPF and by 41% (129 mL) in patients with non-advanced IPF who received pirfenidone.