RESEARCH MONOGRAPH · KDC-MN-246
Vigabatrin
Vigabatrin (Sabril) is a so-called suicide inhibitor of GABA transaminase, the enzyme that breaks down the brain's main inhibitory neurotransmitter. The vinyl group on the molecule converts vigabatrin into a fake substrate that the enzyme attempts to process and is then permanently destroyed by; the only way the brain restores normal GABA breakdown is to manufacture new enzyme from scratch. The result is sustained and powerful elevation of brain GABA levels. It is uniquely effective in infantile spasms (a devastating early-childhood seizure disorder) and refractory complex partial seizures. The catch is severe and irreversible: roughly a third of patients develop permanent visual field constriction from retinal toxicity. That has restricted it to cases where no alternative works. Not stocked by Kodiac. This monograph is provided for research and educational reference.
Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.
GABA transaminase inhibitor (irreversible)
An irreversible suicide inhibitor of GABA transaminase; uniquely effective in infantile spasms and refractory complex partial seizures, limited by retinal toxicity.
Abstract
Vigabatrin ((R/S)-4-aminohex-5-enoic acid; CAS 60643-86-9; molecular formula C6H11NO2; molecular weight 129.16) is a vinyl-GABA suicide inhibitor of GABA transaminase developed at Marion Merrell Dow and approved by the FDA in 2009 under the trade name Sabril (later than European registration in 1989). Mechanism: the vinyl group at the alpha-carbon converts vigabatrin into a substrate that the GABA transaminase enzyme begins to process but cannot release; the result is irreversible covalent enzyme inactivation, requiring de novo enzyme synthesis to recover GABA degradation capacity. The consequence is sustained elevation of brain GABA concentrations. Effective in infantile spasms (West syndrome) where conventional anticonvulsants often fail, and as adjunctive therapy in refractory complex partial seizures. The principal limitation is irreversible bilateral concentric visual field constriction in approximately 30 to 50 percent of long-term users, attributed to retinal photoreceptor damage; the FDA REMS program requires baseline and periodic visual field assessment. Plasma half-life is 5 to 13 hours, but the irreversible enzyme inhibition produces effective activity beyond the plasma window. Used as the canonical GABA transaminase suicide inhibitor.
Mechanism of action
Irreversible suicide inhibition of GABA transaminase via vinyl-GABA mechanism. Sustained elevation of brain GABA concentrations.
Reported research dose ranges
Clinical 1 to 3 g per oral administration daily, in divided doses. Rodent studies 100 to 500 mg/kg/day.
References
- Lippert B, et al. 4-amino-hex-5-enoic acid, a selective catalytic inhibitor of 4-aminobutyric-acid aminotransferase. Eur J Biochem 1977.
- Riikonen R. Long-term outcome of West syndrome: a study of adults with a history of infantile spasms. Epilepsia 1996.
- Wild JM, et al. Vigabatrin and epilepsy: lessons learned. Epilepsia 2009.
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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.