Vigabatrin is an antiepileptic drug that inhibits the catabolism of gamma-aminobutyric acid (GABA) by irreversibly inhibiting GABA transaminase. It is an analog of GABA, but it is not a receptor agonist. Vigabatrin reduced cholecystokinin tetrapeptide-induced symptoms of panic disorder, in addition to elevated cortisol and ACTH levels, in healthy volunteers. Vigabatrin is also used to treat seizures in succinic acid semialdehyde deficiency, which is an inborn neurotransmitter (gamma amino butyric acid) catabolism defect that causes mental retardation, hypotonia, seizures, speech disturbance, and ataxia through the accumulation of 4-hydroxybutyric acid. Vigabatrin inhibits the formation of succinic acid semialdehyde through GABA transaminase inhibition. However, this is in the brain only; it has no effect on peripheral GABA transaminase, so the 4-hydroxybutyric acid keeps building up and eventually reaches the brain.
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