Increase of human plasma GABA by sodium valproate.

gamma-Aminobutyric acid (GABA) was measured in the plasma of volunteers during subchronic treatment with sodium valproate (VPA). After 2 days of oral treatment with 300 mg VPA, t.i.d., the GABA concentration was increased to about 30% compared to 2 control days. This response was similar to that after 2 days of treatment with 600 mg VPA, t.i.d., whereas on the fourth day of treatment with the latter dose, a plasma GABA increase of about 90% was observed.