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High-performance liquid chromatographic method for mycophenolic acid and its glucuronide in serum and urine
D Teshima1, K Otsubo, N Kitagawa
1Department of Hospital Pharmacy, Faculty of Medicine, Kyushu University, Maidashi, Fukuoka, Japan. dteshima@st.hosp.kyushu-u.ac.jp
Objective:
To develop a simple analytical method for monitoring serum and urine concentrations of mycophenolic acid (MPA), an active metabolic constituent of the immunosuppressive pro-drug mycophenolate mofetil, and its glucuronide.
Methods:
Serum samples were prepared by solid-phase extraction (SPE), while urine samples were simply diluted with water. Serum was added to an SPE cartridge, then washed twice with 5% methanol solution. The analytes were eluted with methanol containing benzoic acid as internal standard for mycophenolic acid glucuronide (MPAG). The resultant eluate was directly injected into a high-performance liquid chromatograph (HPLC) to determine MPAG. For the assay of MPA, the remaining eluate was dried under nitrogen and resolved in a mixture of acetonitrile and 20 mM phosphate buffer (pH 3.0).
Results:
The present methods were reproducible and accurate based on the intra- and inter-assay, and had detection limits of 0.225 microg/mL for MPA and 9.0 microg/mL for MPAG. The present methods enabled us to monitor the time course of changes in the concentrations of MPA and MPAG in serum and urine in a patient with a renal transplant during 12 h after ingestion of mycophenolate mofetil.
Conclusion:
The HPLC method described should be useful for the routine monitoring of serum and urine concentrations of MPA and MPAG during immunosuppressive medication for renal transplantation.