Determination of mycophenolic acid (MPA) and its acyl and phenol glucuronide metabolits simultaneously in human plasma by a simplified HPLC method

A simple HPLC method with ultraviolet detection for simultaneous determination of Mycophenolic acid (MPA), its phenol glucuronide metabolite (MPAG) and acyl-MPAG (AcMPAG) in human plasma was established. The plasma samples were prepared with protein-preciptaing reagent, and the supernatant was eluted on Zorbax column (250 mm x 4.6 mm i.d, 5 mm) with 20 mmol/l NaH2PO4 buffer (pH 3.0, adjusted with 20% phosphoric acid) and methanol (45: 55, v/v) at 304 nm. The column temperature was 45 degrees C, and the flow rate was 1.2 ml/min. The assay was linear within the range of 0.2-50 mu g/L for MPA (r = 0.9997), 2.8-531 mu g/L for MPAG (r = 0.9999), and 0.3-24 mu g/L for AcMPAG (r = 0.9994). Mean absolute recovery of MPA and its metabolites and internal standard was 80%. The average recoveries of MPA, MPAG, and AcMPAG were 94.0-101.4, 98.4-101.9, and 96.1-104.2%, respectively. The RSD of within-day and between-day were all lower than 15%. The method described is sensitive, reproducible, and will be useful in TDM or pharmacokinetic studies of MPA.