Simultaneous determination of the plasma concentration in four antiepileptic drugs using high performance liquid chromatography

Objective To establish a method for simultaneously determining the plasma concentration in multiple antiepileptic drugs,such as carbamazepine(CBZ),phenobarbital(PB),nitrazepam(NTZ) and clonazepam(CNZ) using high performance liquid chromatography(HPLC).Methods The serum samples were processed by a certain method,in which the chromatographic column was Novapak C18(150 mm × 3.9 mm,4 μm),the mobile phase was composed of 0.01 mol/L monopotassium phosphate buffer solution(p H2.15) and acetonitrile(29∶ 71),the monitoring wavelength was 223 nm at a flow rate of 1 ml / min,and the column temperature was set at 30 ℃.Results The residual impurities of the processed serum did not interfere with the tested drugs,which were well separated under the chromatographic conditions.The concentration had a stable linear relationship with the peak area in the range of 0.01-10 mg / L(r 0.999 0).Of all the drugs,recoveries of the method were all higher than 90% while the relative standard deviations(RSD) of within-day and between-day were both less than 10%.Conclusion This method was efficient,accurate,simple and practical,and could be applicable for therapeutic drug monitoring.