Xurui Gu1, Shuran Yu2, Qilin Peng1, Mubai Ma1, Yani Hu1, Boting Zhou3. 1. Department of Pharmacy, Xiangya Hospital, Central South University, No. 87, Xiangya Road, Changsha, 410008, Hunan Province, China. 2. Department of Obstetrics and Gynecology, Xiangya Hospital, Central South University, No. 87, Xiangya Road, Changsha, 410008, Hunan Province, China. 3. Department of Pharmacy, Xiangya Hospital, Central South University, No. 87, Xiangya Road, Changsha, 410008, Hunan Province, China. Electronic address: botingzhou0918@csu.edu.cn.
Abstract
AIM: In order to monitor the free concentration of VPA in plasma, a simple and rapid method needs to be developed. METHODS: The free fraction of VPA in plasma was obtained by centrifugal ultrafiltration (CF-UF) devices. Cyclohexanecarboxylic acid was used as internal standard. Valproate in plasma was converted to VPA by sulphuric acid acidification, and dichloromethane was used as solvent for extraction. Nitrogen was the carrier gas, the samples were separated by capillary column, and the flame ionization detector was used to detect VPA fragment ions for quantitative analysis. RESULTS: The assay had good specificity and stability. The linear range of the assay was 0.56-28.11 mg/L. The intra-day and inter-day precision (RSDs) of the assay were all within 15%, and the accuracy (RE) was 2.58%. The recoveries of VPA with three different concentrations were 102.03 ± 1.05, 101.45 ± 2.08 and 102.58 ± 3.38. The results of therapeutic drug monitoring (TDM) in pediatric inpatient group and outpatient group showed significant differences between the two groups (P < 0.001). CONCLUSION: This assay has low cost and good analytical performance, so it can be developed into a routine TDM method of unbound VPA. We recommend the monitoring of unbound VPA concentration in pediatric inpatients during clinical use of VPA.
AIM: In order to monitor the free concentration of VPA in plasma, a simple and rapid method needs to be developed. METHODS: The free fraction of VPA in plasma was obtained by centrifugal ultrafiltration (CF-UF) devices. Cyclohexanecarboxylic acid was used as internal standard. Valproate in plasma was converted to VPA by sulphuric acid acidification, and dichloromethane was used as solvent for extraction. Nitrogen was the carrier gas, the samples were separated by capillary column, and the flame ionization detector was used to detect VPA fragment ions for quantitative analysis. RESULTS: The assay had good specificity and stability. The linear range of the assay was 0.56-28.11 mg/L. The intra-day and inter-day precision (RSDs) of the assay were all within 15%, and the accuracy (RE) was 2.58%. The recoveries of VPA with three different concentrations were 102.03 ± 1.05, 101.45 ± 2.08 and 102.58 ± 3.38. The results of therapeutic drug monitoring (TDM) in pediatric inpatient group and outpatient group showed significant differences between the two groups (P < 0.001). CONCLUSION: This assay has low cost and good analytical performance, so it can be developed into a routine TDM method of unbound VPA. We recommend the monitoring of unbound VPA concentration in pediatric inpatients during clinical use of VPA.