High performance liquid chromatographic determination of cyclosporin A in body fluids

A sensitive, specific and reproducible high performance liquid chromatographic assay method for the determination of a new immunosuppressant, cyclosporin A (CsA), in the biological samples such as human blood, rat plasma and rat lymph has been developed. CsA was extracted with diethyl ether followed by being cleaned up with liquid-liquid extraction procedure using carbon tetrachloride-methanol system, and was chromatographed on a microparticulate CN column with UV detection at 212 nm. The lower detection limit is 100 ng/ml in human blood (from 1.0 ml) and 500 ng/ml in the rat plasma or lymph (from 0.2 ml). This method is sensitive enough for monitoring CsA concentrations in the renal transplant patients in the therapeutic dose range, and is also applicable to the determination of CsA in the rat plasma and lymph samples for the purpose of pharmacokinetic evaluation of several CsA dosage forms in the rats.