Background: Valbenazine, a highly selective vesicular monoamine transporter 2 inhibitor, is approved for the treatment of tardive dyskinesia. This is the first report of long-term effects in adults with tardive dyskinesia.
Methods: Participants with a DSM-IV diagnosis of schizophrenia, schizoaffective disorder, or a mood disorder who completed the 6-week, double-blind, placebo-controlled period of KINECT 3 were eligible to enter the 42-week valbenazine extension (VE) period and subsequent 4-week washout period. The extension phase was conducted from December 16, 2014, to August 3, 2016. Participants who received placebo and entered the VE period were re-randomized 1:1 to valbenazine 80 or 40 mg while others continued valbenazine at the KINECT 3 dose. Safety assessments included treatment-emergent adverse events (TEAEs) and scales for suicidal ideation/behavior, treatment-emergent akathisia or parkinsonism, and psychiatric symptoms. Efficacy assessments included the Abnormal Involuntary Movement Scale (AIMS) and Clinical Global Impression of Change-Tardive Dyskinesia (CGI-TD).
Results: 198 participants entered the VE period, 124 (62.6%) completed treatment (week 48), and 121 (61.1%) completed the follow-up visit after washout (week 52). During the VE period, 69.2% of participants had ≥ 1 TEAE, 14.6% had a serious TEAE, and 15.7% discontinued due to a TEAE. During washout, 13.1% of participants experienced a TEAE. No apparent risk for suicidal ideation or behavior was found. Long-term valbenazine treatment did not appear to induce or worsen akathisia or parkinsonism. Participants generally remained psychiatrically stable during the study. AIMS and CGI-TD measures indicated sustained tardive dyskinesia improvement, with scores returning toward baseline after 4 weeks of valbenazine washout.
Conclusions: The long-term safety and tolerability of valbenazine were generally favorable, and maintenance of treatment effect was apparent with both doses during this long-term study.
Trial registration: ClinicalTrials.gov identifier: NCT02274558.
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