Pirfenidone Products | Cleanchem - Pirfenidone is an antifibrotic drug used to treat idiopathic pulmonary fibrosis (IPF), a lung disease characterized by scarring and stiffening of the lung tissue. It works by inhibiting the production of fibroblasts, which are responsible for the accumulation of scar tissue. Pirfenidone has been shown to slow the progression of the disease and improve lung function in some patients.