Simple and sensitive high-performance liquid chromatographic

A rapid, selective, sensitive, and reproducible reversed-phase HPLC procedure for the quantitative determination of mycophenolic acid (MPA)--an active plasma metabolite of the immunosuppressant mycophenolate mofetil (MMF) in plasma is described. The procedure involves one-step extraction of MPA and the internal standard, standard [RS-60461-000: (E)-6-[1,3-dihydro-4-(4-carboxy-butoxy)-6-methoxy-7-methyl-3-oxo-5-is obenzo-furanyl-4-methyl-4-hexenoic acid] with dichloromethane-dichloroethane (1:1, v/v) at acidic pH. Chromatographic separation consisted of the mobile phase [acetonitrile-0.05% phosphate buffer, pH 3.4 (45:55, v/v)] running through the column (Techopak-10 C18) at flow-rate of 0.8 ml/min. Detection was at UV wavelength of 254 nm. The mean recoveries of MPA and the internal standard at concentrations of 0.1 and 20 microg/ml were 89-98%, and 90-96%, respectively. The within-day coefficients of variation for MPA were 0.3-7.8% and the day-to-day coefficients of variation were 1.1-2.0%. The minimum detectable concentrations for both MPA and the internal standard in plasma were 0.005 microg/ml. The method was found to be suitable for use in clinical pharmacokinetic study.