A specific chymase inhibitor, NK3201, suppresses bleomycin-induced pulmonary fibrosis in hamsters

We evaluated whether a chymase inhibitor, 2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidine-1-yl)-N-[(3,4-dioxo-1-phenyl-7-(2-pyridyloxy))-2-heptyl]acetamide (NK3201), suppressed bleomycin-induced pulmonary fibrosis. Hamsters were orally administered NK3201 (30 mg/kg per day) or placebo, beginning 5 days before intratracheal instillation of bleomycin (10 mg/kg). Four weeks after the instillation of bleomycin, pulmonary chymase activity in placebo-treated hamsters was significantly higher than in control hamsters, whereas the activity in NK3201-treated hamsters was significantly lower than in placebo-treated hamsters. The ratio of fibrotic area to total area in NK3201-treated hamsters was significantly decreased to 54.0% of the ratio in placebo-treated hamsters. Therefore, NK3201 may be useful in the prevention of pulmonary fibrosis.