ZP 1609 Hydrochloride is the hydrochloride form of ZP 1609, which is a small modified dipeptide and has been identified as a potent and selective second generation gap junction modifier with oral bioavailability. It is a pharmalogical agent with a favorable clinical safety profile and potential antiarrhythmic efficacy, which is confirmed in phase I clinical trials. It is used for the treatment of atrial fibrillation. It was developed by Zealand Pharma and was termination in Clinical phase II.