Sequential neuropathology of dogs treated with vigabatrin, a GABA- transaminase inhibitor

J. T. Yarrington, J. P. Gibson, J. E. Dillberger, G. Hurst, B. Lippert, N. M. Sussman, W. E. Heydorn, R. J. Marler

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Vigabatrin (Sabril®) is a γ-aminobutyric acid-transaminase (GABA-T) inhibitor that is effective in the treatment of certain types of drug- resistant or uncontrolled epilepsy but is known to cause microscopic vacuolation (intramyelinic edema) in the brains of treated rats, mice, and dogs. The effects of high oral doses (300 mg/kg/day) of vigabatrin administered orally to Beagle dogs were studied during treatment weeks 1-12 and recovery weeks 13, 14, 16, 20, 24, and 28. Emesis, loose stools, and anorexia and 3 drug-related deaths were observed during the first 4 wk of treatment but were virtually nonexistent thereafter because of adaptation to the drug aided by food supplementation. In more sensitive areas of the brain (columns of the fornix, thalamus, and hypothalamus), microscopic quantitative differences between background vacuolation in controls and drug-related vacuolation in treated dogs could be delineated after 4 wk, generally reached highest levels of severity between 8 and 12 wk, and were reversible upon cessation of dosing. Inhibition of brain GABA-T and elevation of brain GABA were noted after 1 wk of treatment. During the course of treatment vigabatrin ranged between 4-17 nmol/ml (plasma) and 42-1,570 nmol/ml [cerebrospinal fluid (CSF)] while CSF GABA concentrations were 4-32 nmol/ml (treated dogs) and 0.1-0.6 nmol/ml (control dogs). Although the cause of vigabatrin-induced microvacuolation is unknown, the results of the study demonstrated that GABA- T inhibition with subsequent GABA elevation occurred within the first week of treatment and was followed by the onset of detectable microvacuolation several weeks later.

Original languageEnglish (US)
Pages (from-to)480-489
Number of pages10
JournalToxicologic Pathology
Issue number5
StatePublished - 1993


  • brain vacuolation
  • intramyelinic edema
  • reversibility
  • γ-vinyl GABA

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Toxicology
  • Cell Biology


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