Abstract

Title : Agreement of methods to predicting valproate levels
By : Chotika Supakoson and Watsayanan Khamtoem
Degree : DOCTOR OF PHARMACY
Advisor : Dr.Tatta Sriboonruang, Ph.D , Asst.Prof.Dr.Suwanna Phattarabenjaphol, Ph.D and Chompoonuch Werawattanachai, Ph.D
Keywords : Valproate; prediction; serum valproate
   
Therapeutic drug monitoring (TDM) of Valproate (VPA) is a hospital service for monitoring the efficacy and safety of medication. Two methods in TDM service have been used= direct measurement of plasma VPA concentration and calculated VPA concentration by applying pharmacokinetics’ models and parameters. However, there is no the agreement study of these two methods in Thai populations. Objectives= To examine the agreement of these two methods (direct-measured VPA and calculated VPA) in measurement of VPA concentrations. Methods= The study design was retrospective descriptive study. The database of Prasrimahabhodi Hospital was reviewed for one year during 2015. Demographic data, VPA doses, plasma valproate and calculated VPA concentrations were collected from 161 psychiatric inpatients. Bland and Altman plot was used to analyze the agreement of two methods. Results= Most subjects were female (58.4%), mean age, weight and VPA dose were 38.98 ± 12.44 years, 61.68 ± 12.78 kg and 802.17 ± 301.47 mg/day; respectively. All subjects had normal liver and kidney functions. About two-thirds (64.6%) of subjects had VPA concentrations within therapeutic range (50-100 mg/L). In addition, the results has shown the agreement of direct-measured VPA and calculated VPA concentrations with the 95% confidence interval mean of difference (4.56 ± 1.96 (22.31)). Conclusions= Findings indicated that the application of calculated VPA concentration by applying pharmacokinetics’ models and parameters are sufficient when direct measurement of VPA concentrations data is not available.
   
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