In the present study, we evaluated the pharmacokinetics and the inhibitory effect of PFD on human TGFβ1-driven lung fibrosis and compared its therapeutic efficacy by intrapulmonary and oral administration using transgenic mice having established lung fibrosis caused by lung-specific overexpression of the full-length human TGFβ1 gene. The gene discussed is TGFB1; the disease is pulmonary fibrosis.