title: Quantitative determination of azithromycin in human plasma by liquid chromatography-mass spectrometry and its application in a bioequivalence study.
abstract: A sensitive, rapid liquid chromatographic-electrospray ionization mass spectrometric method for determination of azithromycin in human plasma was developed and validated. Azithromycin in plasma (0.2mL) was extracted with methyl tert-butyl ether-hexane (50:50, v/v), organic phase was transferred to another clear 1.5mL Eppendorf tube and evaporated to dryness at 40 degrees C and dissolved in mobile phase, samples were separated using a Thermo Hypersil HyPURITY C18 reversed-phase column (150mmx2.1mm i.d., 5microm), together with a mobile phase containing of 20mM ammonium acetate (pH 5.2)-acetonitrile-methanol (50:40:10, v/v/v) and was isocratically eluted at a flow rate of 0.2mL/min. Azithromycin and its internal standard, clarithromycin, were measured by electrospray ion source in positive selective ion monitoring mode. The method demonstrated that good linearity ranged from 2 to 1000ng/mL with r=0.9977. The limit of quantification for azithromycin in plasma was 2ng/mL with good accuracy and precision. The higher mean extraction recovery, say 81.2% and 75.5% for azithromycin and internal standard (IS), respectively, was obtained in this work. The intra-day and inter-day precision ranged from 4.8% to 8.6% and 6.4% to 10.7% (R.S.D.), respectively. The established method has been successfully applied to bioequivalence study of 2 azithromycin formulations for 24 healthy volunteers.
authors.affiliation: Analytical Testing Center of School of Xiangya Medicine, Central South University, Changsha, Hunan 410078, China. bmchenhmu@yahoo.com.cn
authors.forename: Ben-Mei
authors.initials: BM
authors.lastname: Chen
authors.forename: Yi-Zeng
authors.initials: YZ
authors.lastname: Liang
authors.forename: Xiang
authors.initials: X
authors.lastname: Chen
authors.forename: Shao-Gang
authors.initials: SG
authors.lastname: Liu
authors.forename: Fu-Liang
authors.initials: FL
authors.lastname: Deng
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000493:pharmacokinetics; D017963:Azithromycin / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D017291:Clarithromycin / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013810:Therapeutic Equivalency
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin; D017291:Clarithromycin