Roflumilast is an oral selective phosphodiesterase 4 (PDE4) inhibitor. It is a benzamide compound and is currently the only phosphatase IV (PDE-4) inhibitor approved for oral treatment of respiratory diseases. Through Chemicalbook, it selectively inhibits PDE4 and blocks the transmission of inflammatory response signals, thereby inhibiting lung tissue damage caused by respiratory diseases such as COPD and asthma. It has been shown to inhibit COPD-related inflammation with a new mode of action.