Original Articles: PDF OnlyPrediction of Unbound Serum Valproic Acid Concentration by Using In Vivo Binding ParametersKodama, Yasuo; Kuranari, Masae; Tsutsumi, Kimiko*; Kimoto, Hiroo†; Fujii, Isao‡; Takeyama, MasaharuAuthor Information Departments of Clinical Pharmacy, *Clinical Pharmacology and Therapeutics, and ‡Neuropsychiatry, Oita Medical University, Oita, and †Department of Hospital Pharmacy, University of Yamaguchi, Yamaguchi, Japan Therapeutic Drug Monitoring: October 1992 - Volume 14 - Issue 5 - p 349-353 Buy Abstract In a previous study, we determined the in vivo binding parameters of valproic acid (VPA) to serum proteins in seven healthy young adults at steady state by using the Scatchard equation. To evaluate the ability of the Scatchard binding equation to predict steady-state unbound serum VPA concentrations (Cf), 39 adult patients receiving VPA monotherapy and ranging in age from 16 to 68 years were studied. The correlation between predicted and observed Cf was high (r = 0.865). Mean prediction error, mean absolute error (MAE), and root mean squared error (RMSE) were calculated, and served as a measure of prediction bias and precision. The MAE and RMSE were low (MAE = 12.9 μmol/L, RMSE = 17.7 μmol/L). It is feasible to use the Scatchard binding equation to predict Cf in patients receiving VPA monotherapy. © Lippincott-Raven Publishers.