title: A specific method for the measurement of tacrolimus in human whole blood by liquid chromatography/tandem mass spectrometry.
abstract: Tacrolimus (FK 506) measurement by immunoassays in clinical samples of organ transplant patients often lacks a specific reference method. A method combining liquid chromatography (LC) with tandem mass spectrometry (MS/MS) was developed to quantify tacrolimus in whole blood. Liquid-liquid extraction was performed on 1 ml of sample before narrow-bore LC/MS/MS analysis. Ascomycin was used as an internal standard. The standard curve was composed of seven points ranging from 1 to 50 micrograms/l (average r2 = 0.9999). Limits of detection and quantitation were 0.25 and 0.75 microgram/l, respectively. Imprecision was < 5% across the therapeutic range. Tacrolimus recovery averaged 62%. The most abundant metabolites detected in clinical samples were 13-O- and 15-O-demethyl tacrolimus. This method was used in a comparison study with a microparticle enzyme immunoassay (MEIA): MEIA = 1.03 LC/MS/MS -0.084 (microgram/l), (Sy/x = 1.43), r2 = 0.933. With its high sensitivity and specificity, this LC/MS/MS method presents a good reference method for immunoassay evaluation as well as a valuable tool for metabolism studies.
authors.affiliation: Abbott Diagnostics Division, Abbott Laboratories, Abbott Park, Illinois, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Simpson
authors.forename: H I
authors.initials: HI
authors.lastname: Aboleneen
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016903:Drug Monitoring / Q000379:methods*; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood* / Q000493:pharmacokinetics; D013058:Mass Spectrometry / Q000379:methods*; D016377:Organ Transplantation; D016559:Tacrolimus / Q000097:blood* / Q000493:pharmacokinetics
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus