Author: kodiac

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.