Determination of Valproate Acid in Human Serum by HPLC and Clinical Application

Objective To establish a method for the determination of valproic acid in human serum by HPLC and carry out therapeutic drug monitoring(TDM) of valproic acid in clinical.Methods 2-bromo-4'-ntroacetophenone was derivative reagent and cyclohexanecarboxylic acid was used as the internal standard.The separation was achieved on the Shim-pack C18(150×4.6mm,5μm).The mobile phase was consisted of methanol-water=77:23,the detection wavelength was 265 nm,the flow rate was 1ml/min,and the column temperature was 25℃.Results The retention time of cyclohexanecarboxylic acid and valproic acid was 5.2 min and 8.3 min,respectively.The regression equation of valproic acid was Y=0.0143 X+0.0513 r=0.999 7(n=5).The calibration curves of valproic acid were linear over the range of 10~180 μg/ml.The extraction recovery and method recovery were more than 81.6% and 98.9%,respectively.The relative standard deviation(RSD) of within day and between day were both less than 5.4%.The method was used for monitoring valproic acid concentration of 65 epileptic patients,41 of the patients were found the serum concertration in effective level(50~100 μg/ml),and 24 of the patients lower than effective level.Conclusion This method was rapid,accurate and simple way to measure the concentration of valproic acid in human serum.It is suitable for clinical practical application.