title: Establishment of high-performance liquid chromatography and enzyme multiplied immunoassay technology methods for determination of free mycophenolic acid and its application in Chinese liver transplant recipients.
abstract: The objective of this study is to investigate the correlation between methods of high-performance liquid chromatography (HPLC) and enzyme multiplied immunoassay technology (EMIT) for determination of total mycophenolic acid (tMPA) and free (fMPA) concentration and to study pharmacokinetics of fMPA in Chinese liver transplant recipients. An HPLC method with fluorometric detection and an EMIT assay were established to determine fMPA in plasma ultrafiltrates. Pharmacokinetic parameters of tMPA and fMPA in 51 patients were estimated. The calibration range of fMPA was 0.0025 to 1.0 μg/mL for the HPLC method and 0.0050 to 0.50 μg/mL for the EMIT method. Mean recovery of the two methods was 98.0% and 97.1%, respectively. The intraday and interday coefficient of variations were 0.93% to 3.1% and 1.6% to 2.9% for HPLC and 4.51% to 15.8% and 5.83% to 19.5% for EMIT, respectively. The relationship of the two methods was EMIT = 1.074 × HPLC + 0.582 (r2 = 0.918, n = 470, P < 0.05) for tMPA and EMIT = 1.068 × HPLC + 0.004 (r2 = 0.945, n = 297, P < 0.05) for fMPA. There was a positive mean bias of EMIT for tMPA (27.0%) and fMPA (23.3%). The AUC0-12 of tMPA and fMPA obtained by HPLC in 51 patients was 34.7 ± 11.1 and 0.72 ± 0.38 μg·h/mL, respectively. The free fraction of MPA was 1.60 ± 1.21% (Median:1.36%, interquartile: 0.72, 2.22), [corrected] which was significantly correlated with 7-O-glucuronide conjugate of MPA AUC0-12 (r2 = 0.705, P < 0.001), albumin (r2 = -0.529, P < 0.001), and the clearance of creatinine (r2 = -0.417, r2 = 0.005). Both HPLC and EMIT assay are suitable for the determination of fMPA. A considerable interindividual variability exists in pharmacokinetics of fMPA among Chinese liver transplant recipients. 7-O-Glucuronide conjugate of MPA and albumin concentrations are two factors correlated to fMPA variance.
authors.affiliation: Department of Pharmacy, Ruijin Hospital, Jiaotong University School of Medicine, Shanghai, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Chen
authors.forename: ZhiDong
authors.initials: Z
authors.lastname: Gu
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: WeiXia
authors.initials: W
authors.lastname: Zhang
authors.forename: XiaoJing
authors.initials: X
authors.lastname: Fen
authors.forename: WeiMin
authors.initials: W
authors.lastname: Cai
authors.forename: QiShi
authors.initials: Q
authors.lastname: Fan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D044466:Asian People; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D017248:Enzyme Multiplied Immunoassay Technique; D005260:Female; D005965:Glucuronates / Q000493:pharmacokinetics; D020719:Glucuronides / Q000493:pharmacokinetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000378:metabolism / Q000493:pharmacokinetics*; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000493:pharmacokinetics*; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D005965:Glucuronates; D020719:Glucuronides; D007166:Immunosuppressive Agents; D012709:Serum Albumin; C113145:mycophenolic acid glucuronide; D009173:Mycophenolic Acid