Sabeluzole (R-58,735) is a nootropic and neuroprotective drug which was originally developed for the treatment of Alzheimer's disease, and has subsequently been researched for other applications such as sleep apnoea. It acts primarily as an NMDA antagonist, but other mechanisms of action may also be important. Sabeluzole (R-58,735) is a nootropic and neuroprotective drug which was originally developed for the treatment of Alzheimer's disease, and has subsequently been researched for other applications such as sleep apnoea. It acts primarily as an NMDA antagonist, but other mechanisms of action may also be important.