A comprehensive review of the published assays for the quantitation of the immunosuppressant drug mycophenolic acid and its glucuronidated metabolites in biological fluids

Abstract

Therapeutic use of mycophenolic acid (MPA) is steadily on the rise in combination with other immunosuppressant drugs in transplantation patients. The biotransformation of MPA resulted in the formation of glucuronide metabolites, MPAG and AcMPAG. There are a plethora of assays validated for the analysis of MPA alone or with MPAG/AcMPAG in various biological specimens including plasma/serum, urine, ultrafiltrate, saliva, PBMC, dried blood spots, tissue extract, tumor biopsies and vitreous humor. Based on the need for experimental work, a proper choice of the assay and internal standard may be made using the choices in the literature. While the chemical methods involving high-performance liquid chromatography (HPLC) or LC coupled with triple quadrupole mass spectrometry (LC-MS/MS) are popular, enzymatic assays, in spite of their higher bias, have been used for the routine drug monitoring of MPA. The objectives of the present review are: (a) to provide a focused systematic compilation of the HPLC or LC-MS/MS methods for MPA, MPAG and/or AcMPAG published in the last decade (2005 to current) to enable visual comparison of the methods; (b) to compare and contrast a few enzymatic assays with those of the chemical methods; and (c) to discuss relevant issues/limitations and perspectives on select assays under various subheadings.

Development and validation of a sensitive liquid‐chromatography tandem mass spectrometry assay for mycophenolic acid and metabolites in HepaRG cell culture: Characterization of metabolism interactions between p‐cresol and mycophenolic acid

“…These mass transitions are comparable with previously published literature (Iboshi et al, ; Kawanishi et al, ), indicating common fragmentation patterns of MPA and its metabolites under various experimental conditions. Similar to other studies (Syed & Srinivas, ), the ammonium adduct precursor ions were also identified but ultimately not utilized in our method owing to their relatively weak responses in our experimental conditions. The glucuronide moieties can be subjected to in‐source fragmentation as a result of high temperature or collision energy (Zhang et al, ); therefore, ion source temperature and voltage were further optimized manually to minimize this effect.…”

Single‐dose pharmacokinetics of mycophenolic acid following administration of immediate‐release mycophenolate mofetil in healthy Beagle dogs

“…Blood samples were centrifuged at 3,000 g for 5 min at 4°C. The resulting plasma was transferred to polypropylene tubes containing 10% formic acid to create a 10:1 ratio of plasma to formic acid (Syed & Srinivas, 2016; Upadhyay et al, 2014). The samples were then mixed, placed on dry ice, and stored in a freezer maintained at −80°C until analyzed.…”

Reduction of Dilution Error in Elisas Using an Internal Standard

“…Other analytical methods use internal standards during sample preparation as a routine procedure correct for preparation variability and to ensure accuracy of the measured result [35,36]. Internal standards are routinely included in chromatography and MS assays.…”