ZP 1609, a small modified dipeptide, 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 improves conduction and reduces atrial fibrillation or flutter in the canine sterile pericarditis model. It prevents spontaneous ventricular arrhythmias and reduces infarct size during myocardial ischemia/reperfusion injury in open-chest dogs. It showed consistent efficacy on measures of conduction and AF/AFL inducibility in the canine sterile pericarditis model. It was developed by Zealand Pharma and was termination in Clinical phase II.