title: [Determination of lidocaine and its metabolites in human plasma by liquid chromatography in combination with tandem mass spectrometry].
abstract: OBJECTIVE
  To establish a liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for the determination of lidocaine (LDC) and its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), in human plasma. METHODS; The assay was conducted with an API 3000 HPLC-MS/MS system consisted of a Ultimate C18 column (50 x 4.6 mm, 5 microm). The mobile phase consisted of methanol: 5 mmol/ L ammonium acetate (50:50, pH was adjusted to 5.0 by formic acid) and the flow rate was set at 0.2 mL/min. The alkalinized sample was extracted with ethyl acetate. After evaporation of the organic layer, the residue was dissolved in mobile phase and the drug was determined by HPLC-MS/MS using electrospray ionization.
  
  
  RESULTS
  The calibration curve was linear in a range from 15.625 to 2000 ng/mL for LDC. Linear calibration curves were obtained in the range of 1.5625 to 200 ng/mL for both for MEGX and GX. The limit of quantification for LDC, MEGX and GX was set at 15.625, 1.5625 and 1.5625 ng/mL.
  
  
  CONCLUSIONS
  This method for the quantitative determination of lidocaine and its metabolites in human plasma is simple, rapid, sensitive and accurate. Therefore it can be used for the determination of lidocaine and its metabolites in clinical practice.
authors.affiliation: Institute of Clinical Pharmacology, GCP Center, West China Hospital, Sichuan University, Chendu 610041, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Xiang
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.forename: Qin
authors.initials: Q
authors.lastname: Yu
authors.forename: Mao-Zhi
authors.initials: MZ
authors.lastname: Liang
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Qin
authors.forename: Feng
authors.initials: F
authors.lastname: Nan
mesh_terms: D000779:Anesthetics, Local / Q000097:blood* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D008012:Lidocaine / Q000031:analogs & derivatives / Q000097:blood* / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine; C001306:glycinexylidide; C001173:monoethylglycinexylidide