title: Steady-state kinetics of valproic acid in epileptic patients.
abstract: Pharmacokinetic evaluation and prediction were carried out in 20 epileptic patients. Using conventional pharmacokinetic techniques and a one-compartment model, predicted and observed valproic acid plasma concentrations were compared. Valproic acid assay was performed by gas-liquid chromatography. There was good agreement between predicted and observed plasma concentrations. Most patients had predicted half-lives (t1/2s) of 6 to 8 hr, independent of the plasma concentration of valproic acid. Five patients had predicted t1/2s of 12 hr. The correlation between dose and plasma level was poor. Most patients had valproic acid plasma levels between 55 and 100 microgram/ml. Administration of valproic acid three times a day with determination of individual plasma concentrations offers a reliable method of monitoring. Constant levels are maintained in individual patients, but there is substantial intersubject variation.
mesh_terms: D000293:Adolescent; D000328:Adult; D004827:Epilepsy / Q000097:blood* / Q000188:drug therapy; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D014635:Valproic Acid / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use
chemical_list: D014635:Valproic Acid