The effect of chronic administration of
gamma-vinyl GABA (GVG;
vigabatrin) on levels of neurotransmission-related amino compounds was studied in lumbar cerebrospinal fluid of 65 patients with
complex partial epilepsy. The first sample of cerebrospinal fluid was taken before a 3-month period of treatment with 3 g
gamma-vinyl GABA/day, and the second was taken afterwards. From patients who showed a greater than 50% reduction in
seizures (responders) or marked improvement in global performance, a third sample was taken at the end of the next 3-month phase, during which 3 g or 1.5 g
gamma-vinyl GABA had been administered daily. During treatment with 3 g
gamma-vinyl GABA/day, 55% of the patients showed more than 50% reduction in
complex partial seizures; and at the same time free
GABA, total
GABA,
homocarnosine, and
glycine concentrations in the cerebrospinal fluid increased by 104%, 151%, 194% and 16%, respectively. After reduction of the daily dose to 1.5 g, the levels of free
GABA, total
GABA and
homocarnosine were still increased by 65%, 115% and 102%, respectively.
gamma-Vinyl GABA correlated with the levels of free
GABA (P less than 0.002) and
glycine (P less than 0.001). Concentrations of
homocarnosine at baseline and
homocarnosine and total
GABA during
gamma-vinyl GABA treatment were lower (P less than 0.005) in the group of non-responders than in the responder group.
Glutamic acid,
glutamine,
aspartic acid,
asparagine, and
taurine levels did not change during
gamma-vinyl GABA treatment. In conclusion, administration of
gamma-vinyl GABA reduces epileptic
seizures and produces dosage-dependent increases in levels of free
GABA,
GABA-containing
peptides and of
glycine in cerebrospinal fluid, without concomitant change in levels of
excitatory amino acids.