title: An accurate quantitative LC/ESI-MS/MS method for sirolimus in human whole blood.
abstract: Sirolimus is a widely used immunosuppressant that requires therapeutic drug monitoring (TDM). We optimized a preanalytical procedure that allows for the accurate quantiation of sirolimus in whole blood by LC/ESI-MS/MS with minimal matrix effects. Sirolimus is highly lipophilic, and solvents containing greater than 50% methanol were required to maintain sirolimus recovery. The final pretreatment procedure developed consists of a zinc sulfate protein precipitation, an extraction using octadecyl silyl-silica gel for eliminating water-soluble and hydrophilic compounds, and HybridSPE cartridge treatment to eliminate phospholipids. Using this procedure prior to LC/ESI-MS/MS led to the accurate and reproducible quantitation of sirolimus in human whole blood. The linear range of detection was 0.5-50 ng/mL, a range appropriate for TDM, and the method demonstrated good repeatability and intermediate precision within this quantitative range. In order to investigate the quantitative performance of this method, we compared it to two commercially available sirolimus immunoassays and our previously reported LC/ESI-MS/MS method. The immunoassays gave consistently greater values for the sirolimus concentration, and this may be related to antibody cross-reactivity with sirolimus metabolites and/or other matrix effects. Although our procedure is too long to support real-time TDM for outpatients, it can serve as reference method to assess the performance of other analytical methods that are currently available or may be developed in the future.
authors: Department of Pharmaceutical Sciences, Tohoku University Hospital, Aoba-ku, Sendai, Japan. mano@hosp.tohoku.ac.jp
authors: Nariyasu
authors: N
authors: Mano
authors: Mayumi
authors: M
authors: Sato
authors: Marina
authors: M
authors: Nozawa
authors: Yotaro
authors: Y
authors: Matsumoto
authors: Masaru
authors: M
authors: Mori
authors: Hiroaki
authors: H
authors: Yamaguchi
authors: Junichi
authors: J
authors: Goto
authors: Miki
authors: M
authors: Shimada
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007118:Immunoassay; D015203:Reproducibility of Results; D020123:Sirolimus / Q000097:blood* / Q000737:chemistry; D052616:Solid Phase Extraction; D012995:Solubility; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D013997:Time Factors
chemical_list: D020123:Sirolimus