Simultaneous determination of five anti-epilepsy drugs in human plasma using HPLC-MS

Abstract

A new liquid chromatography-mass spectrometry method for the determination of carbamazepine,clonazepam,alprazolam,estazolam and phenytoin in human plasma has been developed by using diazepam as internal standard.Chromatographic separation was performed on a 3.5 μm Zorbax SB-C18 column(30 mm × 2.1 mm) with a mobile phase consisting of methanol and aqueous 25 mM ammonium acetate using gradient elution.A diethyl ether extraction method was used for the extraction of five anti-epilepsy drugs.Final extract was injected for analysis for LC-MS with MS2 mode.The method was validated within the concentration range of 50?5000 ng/mL for five anti-epilepsy drugs.The precision of the assay(RSD%) was less than 10% at all concentration levels within the tested range.The method recoveries for all samples were more than 90%.The results clearly indicate that the method is specific,sensitive and accurate,and suitable to study the pharmacokinetics,adjust the dosage for individual administration,and monitor the drug-concentration and drug abuse of the five anti-epilepsy drugs.