E-4031 is an experimental class III antiarrhythmic drug that blocks potassium channels of the hERG-type.

[1] E-4031 is a synthesized toxin that is a methanesulfonanilide class III antiarrhythmic drug.

hERG channels (Kv11.1) mediate the IKr current, which repolarizes the myocardial cells.

[7][14] In non-cardiac cells, blocking Ikr has a different effect: it increases the frequency of action potentials.

So far, one clinical trial has been conducted to test the effect of E-4031 on prolongation of the QT-interval.