A high-performance liquid chromatographic assay for CI-973, a new anticancer platinum diamine complex, in human plasma and urine ultrafiltrates

CI-973 is a new platinum compound with antitumor properties that is currently undergoing phase II clinical trials. A high-performance liquid chromatographic (HPLC) assay was developed and validated for ultrafiltrates of human plasma and urine to support phase I clinical trials. Plasma ultrafiltrate (0.5 ml) was extracted using C18 solid-phase cartridges. Urine was diluted 10-fold and extracted first with SAX solid-phase cartridges and then with C18 cartridges. For both matrices, the eluate from the C18 cartridges was injected directly. A Whatman PAC 10 column (4.6 x 250 mm, 10-microns particle size) and ultraviolet detection at 205 nm were used for both analyses. The mobile-phase buffer was 0.05 M sodium perchlorate (pH 2.3). The mobile-phase acetonitrile:buffer ratio, column temperature, and flow rate were 89:11 (v/v), 40 degrees C, and 2.0 ml/min, respectively, for the plasma ultrafiltrate assay and 85:15 (v/v), 50 degrees C, and 1.0 ml/min, respectively, for the urine ultrafiltrate assay. Standard curves were linear from 0.25 to 500 micrograms/ml and from 1.0 to 250 micrograms/ml for the plasma and urine assays, respectively. The accuracy of the assay lay within 4.5% of the nominal values, and the precision was 6.2%; the recovery of CI-973 varied from 79.2% to 105%. CI-973 remains stable in plasma for at least 6 h, at room temperature, in ultrafiltrates of both matrices for at least 15 days at -72 degrees C, and in water for at least 6 months at -72 degrees C.