Human brain, plasma, and cerebrospinal fluid concentration of sodium valproate after 72 hours of therapy.

Nine neurosurgical patients suffering from a variety of brain tumors were studied. Sodium valproate was given for 3 days before surgery. At craniotomy, sections of brain and samples of cerebrospinal fluid (CSF) and plasma were obtained and assayed for sodium valproate concentrations. Brain levels were 6.8 to 27.9% of plasma concentrations, and CSF levels were 7.6 to 25.0% of plasma levels. There was a significant correlation between brain and CSF levels and plasma on Spearman ranking. These results confirm that valproate is not selectively concentrated in brain fractions, and the concentration in brain is related to the free anticonvulsant level in plasma.