For a study, the researchers sought to conduct a single-arm, open-label extension (OLE) study to determine the long-term efficacy and safety of deutetrabenazine. Patients who completed the pivotal studies were eligible to participate in the single-arm OLE study, which titrated up to 48 mg/day based on dyskinesia control and tolerability. The change in total motor AIMS score, Clinical Global Impression of Change (CGIC) and Patient Global Impression of Change (PGIC), and quality of life (QOL) assessments were used to determine efficacy. Adverse event (AE) incidence was measured using exposure-adjusted incidence rates and safety scales. About 343 patients were enrolled in the trial (6 patients were excluded). The mean SE change from baseline in total motor AIMS score was between -6.6 and 0.37 at Week 145 (mean dose: 39.4±0.83 mg/day), and 67% of patients obtained a 50% improvement in total motor AIMS score. According to CGIC and PGIC, 73% and 63% of patients had treatment success. There were also advances in QOL. Deutetrabenazine was generally well tolerated, with few mild-to-moderate adverse events (AEs) and no new safety signals; most safety scales remained unaltered over time. Long-term deutetrabenazine medication was associated with a sustained improvement in AIMS scores, indicating clinically relevant long-term benefit, and was usually well tolerated. Deutetrabenazine may provide increased benefit over time without increasing the dose, according to the outcomes.