Real-World Experiences with VMAT2 Inhibitors in Pediatric Hyperkinetic Movement Disorders.

Background: Vesicular monoamine transporter 2 (VMAT2) inhibitors are often prescribed for the treatment of hyperkinetic movement disorders such as tics, stereotypy, tardive dyskinesia and chorea. These dopamine depleters have been FDA approved in adults for the treatment of chorea in Huntington's disease and tardive dyskinesia. Use of VMAT2 inhibitors in pediatric hyperkinetic movement disorders, however, is limited due to lack of pediatric FDA approval. We review the real-world prescribing practices and patient experiences with VMAT2 inhibitors in children. Methods: We performed a retrospective chart review of patients treated with VMAT2 inhibitors at a pediatric movement disorders clinic from 2011 to 2023. Demographics, indication, medical history, and clinical notes were reviewed. Results: We identified 340 pediatric patients (65.3% male, average age 11.9 years) who had been prescribed a VMAT2 inhibitor for a variety of hyperkinetic movement disorders (359 total prescriptions) at our large pediatric movement disorders center. Of the 359 prescriptions for VMAT2 inhibitors, 94% included tetrabenazine, 4.6% deutetrabenazine, and 1.4% valbenazine. Most common clinical indication was tics (73.5%), followed by chorea (9.1%) and self-injurious stereotypy (7.1%). Of these prescriptions, 75.8% (N = 275) successfully commenced treatment. Most patients (62.8%) had clinical improvement with an average Clinical Global Impression-Improvement of 1.8 (±1.2), indicating "very much" or "much" improved, but 11.5% experienced no improvement in symptoms. Most patients (63.9%) reported some side effects, most commonly drowsiness; however, only 35 (10.1%) necessitated discontinuation due to side effects. Seven patients were transitioned from tetrabenazine to deutetrabenazine with resolution of side effects, and one to valbenazine with similar effect. Of the 359 prescriptions, 194 (54%) experienced at least one denial from insurance companies; 24.2% were unable to initiate treatment due to barriers such as insurance denials and 19.6% expressed financial concerns regarding medication affordability. Discussion: Our study suggests that VMAT2 inhibitors are effective for treating pediatric hyperkinetic movement disorders. Furthermore, this study provides insights into barriers to access to these drugs by pediatric patients.