The Free Fraction of Valproic Acid in Tears, Saliva, and Cerebrospinal Fluid

Abstract
Valproic acid (VPA) was determined by EMIT [enzyme multiplied immunoassay technique] assay in plasma, tears, saliva and CSF of patients with epilepsy. Closer correlation was shown between tear/plasma and tear/CSF ratios than between saliva/plasma and saliva/CSF ratios. The VPA CSF/serum ratio was in good aggrement with data in the literature. Salivary levels were extremely erratic, while those for tears were much more reliable. Determination of VPA in tears is the best method of stuyding the VPA-free fraction in cases in which investigations of protein bindng of the drug are necessary.