PG531

PG531 is an investigational small molecule developed by Celon Pharma S.A. for the treatment of neuropsychiatric and neurological disorders. It is primarily being evaluated for indications such as schizophrenia, psychotic disorders, and levodopa-induced dyskinesia in Parkinson's disease. PG531 is part of a series of next-generation compounds, including PG511 and PG521, that are being compared to Celon's more advanced candidate PG203 (CPL500036). PG203 is a known inhibitor of phosphodiesterase 10A (PDE10A), an enzyme highly expressed in the striatum that regulates cyclic nucleotide signaling (cAMP and cGMP). By targeting PDE10A, PG531 aims to modulate dopaminergic and glutamatergic neurotransmission to alleviate symptoms of psychosis and motor complications. As of early 2025, PG531 is undergoing Phase 1 clinical evaluation in healthy volunteers to characterize its safety, tolerability, and pharmacokinetic profile relative to earlier compounds in the pipeline.