An orally active synthetic antifibrotic agent structurally similar to pyridine 2,4-dicarboxylate. Pirfenidone inhibits fibroblast, epidermal, platelet-derived, and transforming beta-1 growth factors, thereby slowing tumor cell proliferation. This agent also inhibits DNA synthesis and the production of mRNA for collagen types I and III, resulting in a reduction in radiation-induced fibrosis. or A substance that is being studied in the prevention and treatment of scar tissue caused by radiation therapy. It belongs to the family of drugs called anti-inflammatory agents.