title: A novel antibiotic bone assay by liquid chromatography/tandem mass spectrometry for quantitation of tigecycline in rat bone.
abstract: Tigecycline (Tygacil) is a first-in-class, broad spectrum antibiotic with activity against antibiotic-resistant organisms. In rats and humans, tigecycline readily distributes to bone tissue but its accuracy of quantitation via liquid chromatography/mass spectrometry (LC/MS/MS) is hindered by a low extraction recovery when using a conventional plasma extraction method. To overcome this issue, we have identified an effective extraction solvent for quantitation of tigecycline in rat bone. The current LC/MS/MS bone assay is novel, simple, and sensitive, and has a wide linear range of 50-10,000 ng/g. The assay requires homogenization of the rat bone in a strong acidic-methanol extraction solvent, centrifugation of the bone suspension, separation of the supernatant with liquid chromatography, and detection of tigecycline with tandem mass spectrometry. The incurred pooled rat bone samples obtained from rats given 3mg/kg/day of [(14)C]-tigecycline and non-radio-labeled tigecycline were analyzed with the current method. The absolute extraction recovery of the bone assay for tigecycline was 77.1%. The intra-day accuracy ranged from 91.7 to 106% with precision (CV) of 1.9-10.7%, and inter-day accuracy ranged from 96.1 to 100% with a precision of 6.3-8.7%. In addition, biological activity was demonstrated for the tigecycline extracted from incurred rat bone. This bone assay provides an important analytical tool for the determination of drug concentrations (especially, antimicrobials) in rodent bone tissues and has served as the foundation of development and validation of a similar bone assay for tigecycline in human bone tissues.
authors.affiliation: Bioanalytical R & D, Wyeth Research, 401 North Middletown Road, Pearl River, NY 10965, USA. Jia@wyeth.com
authors.forename: Allena J
authors.initials: AJ
authors.lastname: Ji
authors.forename: James P
authors.initials: JP
authors.lastname: Saunders
authors.forename: Nandan D
authors.initials: ND
authors.lastname: Wadgaonkar
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Petersen
authors.forename: Kenneth
authors.initials: K
authors.lastname: O'Leary
authors.forename: Williams E
authors.initials: WE
authors.lastname: McWilliams
authors.forename: Peter
authors.initials: P
authors.lastname: Amorusi
authors.forename: Mauricio
authors.initials: M
authors.lastname: Leal
authors.forename: Eric N
authors.initials: EN
authors.lastname: Fluhler
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D001409:Bacillus cereus / Q000187:drug effects; D001681:Biological Assay; D001842:Bone and Bones / Q000737:chemistry*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D003627:Data Interpretation, Statistical; D008297:Male; D008911:Minocycline / Q000031:analogs & derivatives* / Q000032:analysis; D011786:Quality Control; D051381:Rats; D017207:Rats, Sprague-Dawley; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D012996:Solutions; D000078304:Tigecycline; D008911:Minocycline