Christians U, Radeke H H, Kownatzki R, Schiebel H M, Schottmann R, Sewing K F
Institut für Allgemeine Pharmakologie, Medizinische Hochschule Hannover, Germany.
Clin Biochem. 1991 Jun;24(3):271-5. doi: 10.1016/0009-9120(91)80019-y.
Metabolism of FK506, a 23 member macrolide under clinical investigation as immunosuppressant after transplantation, was studied using human liver microsomes. Two fractions isolated by semi-preparative HPLC were identified by negative fast atom bombardment mass spectrometry as FK506 metabolites with mass peaks at m/z = 790 indicating demethylation of the mother compound. The immunosuppressive activity of one metabolite was evaluated in a ConA-stimulated peripheral rat lymphocyte assay. FK506 had an IC50 of 0.186 nmol/L and the metabolite tested of 1.89 nmol/L.