The human ether-a-go-go related gene (hERG) potassium channel is a voltage-gated ion channel found in the heart, essential for cardiac repolarisation. The channel has a large inner cavity making it sensitive to drug binding. Inhibition of the hERG ion channel results in decreased function and produces Long QT Syndrome (LQTS) leading to potentially fatal cardiac arrhythmias. Cardiovascular safety issues are a major cause for the attrition of drug development candidates and testing cardiac risk via the hERG ion channel is recommended during the drug discovery process.