Aptiganel is a drug which acts as a noncompetitive NMDA antagonist. It has neuroprotective effects and was researched for potential use in the treatment of stroke

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

, but despite positive results in animal studies, human trials showed limited efficacy, as well as undesirable side effects such as sedation

Sedation

Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...

 and hallucinations, and clinical development was ultimately not continued.