The mechanism of tardive dyskinesia (TD) is complex and not well understood. Dopamine-receptor blockade in the nigrostriatal pathway may lead to a hyperdopaminergic state that can interfere with mechanisms of movement control, leading to TD. Medications for the treatment of movement disorders, including TD, typically require fine-tuning of doses to optimize control of abnormal movements; however, doses are often not titrated sufficiently. The vesicular monoamine transporter 2 inhibitor deutetrabenazine is an FDA-approved treatment for TD in adults. This post hoc analysis examined dosing patterns in patients with TD according to baseline Abnormal Involuntary Movement Scale (AIMS) item 8 score, a clinician-rated global judgment of the overall severity of abnormal movements.

Patients who completed the pivotal 12-week studies, ARM-TD and AIM-TD, were eligible to enroll in the 3-year, open-label extension study. Deutetrabenazine was initiated at 12 mg/day and titrated in a response-driven manner on a weekly basis in intervals of 6 mg/day for 6 weeks, up to a maximum dose of 48 mg/day, based on dyskinesia control and tolerability. Further dose adjustments during the long-term maintenance period were permitted on a weekly basis. Subgroups were defined by AIMS item 8 scores of either 0/1/2 or 3/4 at baseline. Total daily dose categories and treatment exposure over time were evaluated in each subgroup.

A total of 336 patients were included in the analysis (baseline AIMS item 8 scores 0/1/2, n = 117; scores 3/4, n = 219). At week 15, the proportions of patients by deutetrabenazine total daily dose (mg) for scores 0/1/2 and 3/4, respectively, were: <24, 10% and 3%; ≥24 to ≤36, 41% and 48%; >36 to ≤48, 49% and 49%. At week 54, proportions by total daily dose (mg) for scores 0/1/2 and 3/4, respectively, were: <24, 11% and 4%; ≥24 to ≤36, 42% and 41%; >36 to ≤48, 46% and 55%; >48, 1% and 0. Similar patterns were observed at weeks 106 and 145 across total daily dose categories. For scores 0/1/2, mean ± SE total daily dose (mg) at weeks 15, 54, 106, and 145, respectively, was 36.9 ± 1.04 (n = 108), 37.1 ± 1.22 (n = 90), 37.7 ± 1.32 (n = 76), and 37.9 ± 1.44 (n = 64). For scores 3/4, mean ± SE total daily dose (mg) at weeks 15, 54, 106, and 145, respectively, was 39.2 ± 0.65 (n = 186), 39.8 ± 0.75 (n = 150), 40.3 ± 0.88 (n = 112), and 40.5 ± 0.99 (n = 97).

Dosing decisions in the treatment of TD are individualized, as treatment response is likely driven by complex factors. Findings from this analysis suggest that in order to achieve adequate control of TD symptoms, patients benefit from response-driven titration of deutetrabenazine to doses >24 mg/day, regardless of the baseline severity of abnormal movements assessed by AIMS item 8. These results highlight the importance of patient-driven titration of deutetrabenazine until adequate movement control is achieved, while maintaining safety/tolerability in the treatment of TD.

Teva Pharmaceutical Industries Ltd., Petach Tikva, Israel