BIOANALYTICAL METHODS FOR IODIXANOL AND THEIR APPLICATION TO STUDIES ON METABOLISM AND PROTEIN-BINDING

The iodine-specific detection techniques X-ray fluorescence spectromet ry, neutron activation analysis and radiochemical detection of I-125-l abelled substance are well suited for quantification of iodixanol in b iological samples. The limit of detection is 60 mu g iodixanol/ml for X-ray fluorescence analysis and 1 to 10 mu g iodixanol/ml for neutron activation analysis. Reversed-phase high-performance liquid chromatogr aphy (HPLC) has been employed when selective determination of iodixano l was needed for identificational purposes or when quantification of v ery small amounts of iodixanol was essential. An optimized HPLC method for quantification of iodixanol in rat serum and urine is presented. The limit of detection for this method is 0.20 mu g iodixanol/ml for r at serum and 3.0 mu g iodixanol/ml for rat urine. When samples were an alyzed by HPLC and thin layer chromatography, no metabolites of iodixa nol were observed in rat, monkey or human urine, or in rat kidney and bile. Studies with equilibrium dialysis and HPLC determination of iodi xanol showed no protein binding of the contrast agent in human plasma; the 95% confidence interval for the result was 0.0+/-2.1%.