title: Safety and Efficacy of Tetrabenazine and Use of Concomitant Medications During Long-Term, Open-Label Treatment of Chorea Associated with Huntington's and Other Diseases.
abstract: BACKGROUND
  Although tetrabenazine, a drug that depletes presynaptic dopamine by inhibiting vesicular monoamine transporter 2 (VMAT2), was approved by the U.S. Food and Drug Administration in 2008 for the treatment of chorea associated with Huntington's disease (HD), there is a paucity of data on its long-term efficacy and safety.
  
  
  METHODS
  Approximately 2,000 patients with a variety of hyperkinetic movement disorders had been treated with open-label tetrabenazine at the Movement Disorders Clinic, Baylor College of Medicine, since 1979. Tetrabenazine was usually started at 12.5 mg/day, and the dosage was gradually increased (up to 300 mg/day). Responses were rated by the investigator 1-5, with 1  =  marked chorea reduction, excellent improvement in function; 2  =  moderate chorea reduction, very good improvement in function; 3  =  fair chorea improvement, only mild improvement in function; 4  =  poor or no response for chorea and function; and 5  =  worsening chorea, some functional deterioration. Efficacy and safety were analyzed retrospectively.
  
  
  RESULTS
  By 2004, 98 HD chorea patients had received tetrabenazine for a mean of 3.1 years (range ≤1-11.4 years). Of those with valid ratings, 75% had either marked or very good responses (rating 1 or 2) at their optimal dosages. The most common adverse events occurring in ≥5% of the patients were somnolence (39%), insomnia (33%), depression (31%), accidental injury (26%), and dysphagia (19%). Efficacy and safety were comparable to results for non-HD chorea patients.
  
  
  CONCLUSIONS
  Tetrabenazine treatment was associated with long-term improvement in chorea. Adverse event rates were comparable to those reported from controlled trials.
authors.affiliation: Lundbeck LLC, Deerfield, Illinois, United States of America.
authors.forename: Vivienne
authors.initials: V
authors.lastname: Shen
authors.forename: Kathleen
authors.initials: K
authors.lastname: Clarence-Smith
authors.forename: Christine
authors.initials: C
authors.lastname: Hunter
authors.forename: Joseph
authors.initials: J
authors.lastname: Jankovic
keywords: Huntington’s disease; VMAT2 inhibition; chorea; clinical trial; monoamines; tetrabenazine