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I41 Post-marketing adverse events (AES) associated with tetrabenazine (TBZ): findings using FDA’s adverse event reporting system (FAERS)
  1. Daniel O Claassen1,
  2. Ravi Iyer2,
  3. Mo Dimbil3,
  4. Abril Giron3,
  5. Lisa De Boer4,
  6. Sanjay Gandhi2,
  7. Keith B Hoffman3
  1. 1Vanderbilt University Medical Centre, Nashville, Tennessee, USA
  2. 2Teva Pharmaceutical Industries, Frazer, Pennsylvania, USA
  3. 3Advera Health Analytics, Santa Rosa, California, USA
  4. 4Teva Pharmaceuticals, La Jolla, California, USA


Background In clinical trials of patients with Huntington’s disease (HD), treatment with TBZ resulted in more neuropsychiatric AEs compared to placebo, including insomnia, somnolence, anxiety, depression, and agitation.

Aim To summarise post-marketing reports of AEs associated with TBZ by analysing case reports from FAERS.

Methods FAERS data for branded TBZ (Xenazine®) included case reports meeting minimal key identification field criteria: individual safety report number, patient number, drug sequence identification, and MedDRA AE term. RxFilter was used for standardisation of case report data and was applied to TBZ data to analyse AEs with relevant regulatory interest. Primary suspect counts of AEs in which TBZ is suspected as the causative agent and calculation of disproportional reporting rates were performed to identify potential safety signals.

Results Post-marketing safety data for TBZ included many of the most frequent AEs as reported in the pivotal trial, including depression, somnolence, fatigue, fall and insomnia, indicating a consistency between these two sources. Of the AEs that were common between clinical trial and post-marketing observations, depression was most frequently reported in the post-marketing data. In clinical trials, depression was the fourth most commonly reported AE and was preceded by sedation/somnolence, insomnia and fatigue. A disproportionality analysis identified high reporting odds ratios (>2) for some neuropsychiatric AEs, indicating that there is a higher-than-expected reporting rate.

Conclusions Although post-marketing AE reporting is voluntary and thus a potentially more conservative estimate of safety signals compared with clinical trials, there was consistency between TBZ-associated AEs reported in the clinical trial setting and spontaneous post-marketing AE reporting. The real-world spontaneous AE reporting could be a useful data source to guide informed patient care decisions.

  • Adverse Events
  • Tetrabenazine

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