Simultaneous determination of mycophenolic acid and its glucuronide conjugate in human plasma by a single-run ion-paring method.

A quick and robust HPLC method for simultaneous determination of plasma concentrations of mycophenolic acid (MPA) and its glucuronide conjugate (MPAG) is described. Using tetrabutylammonium dihydrogen phosphate as ion-paring reagent in the mobile phase, concentrations for both MPA and MPAG can be determined in a single HPLC run on a reversed-phase C18 column at 254 nm. The method is reproducible and accurate, with lower limits of quantification of 0.100 microg/ml for MPA and 0.800 microg/ml for MPAG. The quantification ranges of the method are 0.100-40.0 microg/ml for MPA and 0.800-400 microg/ml for MPAG using a 0.5-ml aliquot in the analysis.