Carison I. Identification and analysis of nine metabolites of cyclosporine in whole blood by liquid chromatography. 1: Purification of analytical standards and optimization of the assay. Clin Chem

We used a “high-performance ” liquid-chromatographic as-say [for parent cyclosporine (GsA) and nine metabolites] and a radioimmunoassay to detail the diversity of results among whole-blood samples from patients with transplanted organs. Heterogeneous populations of metabolites in samples col-lected just before the next dose of GsA were detected by HPLC, with GsA, M17, Ml, or M8 predominating; M21, M203-218, MUNDF1, and M18 were detected in lesser amounts. Results by HPLC vs AlA for GsA or for individual metabolites vs GsA (or AlA) were diverse, with correlation coefficients (r) ranging from 0.058 to 0.933. AlA vs HPLC(sum of GsA + metabolites) gave thebestcomparison (slope = 0.931,y-intercept14 p.gIL, r = 0.933); but the scatterofdataabouttheregressionlineremainedsignificant = 132 jzg/L). Most important, R1AJHPLC(CsA) v