Phosphodiesterase-IN-5 is a potent, orally active and selective phosphodiesterase 10A (PDE10A) inhibitor with an IC50 of 6.2 nM. Phosphodiesterase-IN-5 shows >1612-fold selectivity over other PDEs. Phosphodiesterase-IN-5 exhibits potent antifibrotic efficacy in a Bleomycin (BLM) (HY-108345)-induced murine model of pulmonary fibrosis (PF) by blocking myofibroblast differentiation via the cAMP/PKA/CREB signaling pathway. Phosphodiesterase-IN-5 can be used for the research of PF[1].