Routine monitoring of cyclosporine in whole blood and in kidney tissue using high performance liquid chromatography.

A simple isocratic reversed-phase high pressure liquid chromatographic procedure for the specific estimation of cyclosporine in 1 mL of whole blood using cyclosproin D as internal standard is described. The chromatographic conditions chosen afford a high degree of resolution and sensitivity, a prolonged analytical column life (four months), and complete analysis of ether extracts within 8 min. The limit of detection is 10 micrograms/L. Thirty-five patient samples can be analyzed in a single batch with a turnaround time of 7 hr. This method has been in use in the authors' therapeutic drug monitoring laboratory for nearly two years. It can be simply adapted for the analysis of cyclosporine in kidney samples as a possible aid in the diagnosis of therapeutic failure or toxicity in renal allograft recipients. Examples are given to illustrate the usefulness of frequent monitoring of cyclosporine in stabilizing graft function after organ transplantation.