AZD-1305

AZD-1305 is an investigational small molecule antiarrhythmic agent developed by AstraZeneca for the management and reversal of cardiac arrhythmias, specifically atrial fibrillation and atrial flutter. It acts as a multi-ion channel blocker with class III anti-arrhythmic activity. The drug blocks the human ether-a-go-go-related gene (hERG) potassium channel (IKr), voltage-gated sodium channels (Nav1.5), and L-type calcium channels. By inhibiting these ion channels, AZD-1305 prolongs action potential duration, increases refractory period, delays repolarization in cardiac myocytes—particularly in the atria—and suppresses abnormal electrical activity that can lead to arrhythmias. Its effects are more pronounced in atrial than ventricular tissue, providing some degree of atrial selectivity[2][4][5]. Despite showing efficacy in converting atrial fibrillation to sinus rhythm, clinical development was discontinued due to concerns over QT interval prolongation and risk of torsade de pointes[2][8].