Current cardiac safety testing regimes have successfully prevented new drugs coming to market with unknown proarrhythmic risk. However, they are expensive and time-consuming, and an over-reliance on hERG liability as a marker for proarrhythmia has led to exclusion of useful chemical scaffolds from further drug development. In addition, the focus on hERG ignores the risk posed by potential drug interactions with multiple cardiac ion channels (MICE) that can alter cardiac action potentials.

The TTX-resistant sodium channel Nav1.8 is expressed in peripheral sensory nociceptors and is implicated in a range of inflammatory and visceral pain conditions such as irritable bowel syndrome (IBS)1. Nav1.8 channel function in sensory neurons changes after injury or inflammation, with a redistribution from the soma to axons and upregulated activity through inflammatory mediators and signalling pathways.