[Neuronal potassium channel opening with flupirtine]

Abstract

The spectrum of action of flupirtine includes analgesic, muscle-relaxant and neuroprotective properties. The substance's mechanism of action has yet to be fully explained. Over the past few years, however, evidence has accumulated that flupirtine interacts with the glutamatergic N-Methyl-D-Aspartate (NMDA) receptor. Although it was not possible to demonstrate a direct effect on the NMDA receptor, all of the findings pointed to an indirect influence on the NMDA receptor in the sense of a functional NMDA antagonism. It was thus postulated that a site of action "up- or downstream" of the NMDA receptor is influenced. Such a site of action proved to be the G-protein-activated inwardly rectifying K+ channels (GIRK), the opening of which leads to a stabilization of the resting membrane potential of neuronal cells and thus causes an indirect inhibition of the NMDA receptor. At therapeutically relevant concentrations, flupirtine is a neuronal potassium channel opener. This mechanism may explain the spectrum of action of flupirtine. Selective neuronal potassium channel opening (SNEPCO) thus proves to be a new principle of action, making flupirtine the prototype of a new substance class with analgesic, muscle-relaxant and neuroprotective properties. The experimental basis for this working hypothesis and the resulting model concepts are presented from the perspective of a four-stage approach.