RT Journal Article
SR Electronic
T1 Characterization of glucuronidated phase II metabolites of the immunosuppressant cyclosporine in urine of transplant patients using time-of-flight secondary-ion mass spectrometry.
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1151
OP 1154
VO 24
IS 10
A1 K Meyer
A1 M Fobker
A1 U Christians
A1 M Erren
A1 K F Sewing
A1 G Assmann
A1 A Benninghoven
YR 1996
UL http://dmd.aspetjournals.org/content/24/10/1151.abstract
AB The immunosuppressant, cyclosporine, is metabolized in the liver and small intestine to > 30 metabolites. Metabolism and immunosuppressive and toxic potentials of the metabolites are still unclarified. Therefore, search and determination of new metabolites remain an important part of cyclosporine research. In this study, cyclosporine metabolites were determined in 42 urine samples of transplant patients using time-of-flight secondary-ion MS. Besides the known metabolites of phase I and phase II, other groups of new phase II metabolites were detected, and most of them were identified as glucuronidated phase I metabolites. All metabolites were found in the urine of heart, kidney, and bone marrow graft patients, with frequencies in the range of 74% and 12%. The most intensive group of these metabolites was also detected in a HPLC fraction, together with the known glucuronidated AM1c. The concentration of this new metabolic group could be estimated to < or = 5/ml. In conclusion, this work demonstrated that time-of-flight secondary-ion MS is a powerful tool in pharmacological investigations. Furthermore this study showed that phase II metabolism is an important metabolic pathway of cyclosporine in transplant patients.