Comparison of cyclosporine determinations in whole blood by three different methods. HPLC, 125I RIA and 3H RIA

The authors have analyzed and compared the cyclosporine concentrations in whole blood specimens from pediatric renal transplant patients using three different methods: high-performance liquid chromatography (HPLC) (5u C18 reverse-phase column), 3H radioimmunoassay (RIA) (Sandoz, E. Hanover, NJ), and 125I RIA (substituted 3H-tracer in Sandoz Kit with 125I tracer made by Immuno Nuclear Corporation, Stillwater, MN). Results obtained by the 125I RIA correlated well with results obtained by the 3H RIA. Both RIA methods had similar correlation with the HPLC method. The 125I RIA method showed higher sensitivity and greater precision than the 3H RIA method. The authors conclude that the 125I RIA method can be used for cyclosporine determination in whole blood specimens. The use of the 125I RIA provides a simple and rapid method with higher counting efficiency and less background quenching than the 3H RIA method, which requires cumbersome liquid scintillation counting procedures.