NBI-98854 is primarily used in the treatment of tardive dyskinesia, a neurological disorder characterized by repetitive, involuntary movements. It functions as a vesicular monoamine transporter 2 (VMAT2) inhibitor, which helps regulate dopamine levels in the brain, thereby reducing the severity of symptoms. This compound is particularly beneficial for patients who have developed tardive dyskinesia as a side effect of long-term antipsychotic medication. Its targeted mechanism of action minimizes the risk of exacerbating psychiatric conditions, making it a valuable therapeutic option for managing this challenging disorder.