Determination of cyclosporin A in human and mouse plasma by reversed-phasehigh-performance liquid chromatography

An isocratic reversed-phase high-performance liquid chromatographic method with ultraviolet detection at 227 run has been validated for the determinat ion of cyclosporin A in human and mouse plasma. The cyclosporin D analog PS C 833 was used as internal standard. Plasma samples were pretreated by Equi d-liquid extraction with diethyl ether. A good chromatographic separation b etween cyclosporin A, the internal standard and two potentially interfering endogenous peaks was achieved using a stainless steel column packed with 5 mum Nova-Pak phenyl material operated at 72 degreesC, and a mobile phase c onsisting of acetonitrile-methanol-water (20:52:28, v/v/v). The calibration curve for cyclosporin A in human plasma was linear over the tested concent ration range of 0.11 to 5.34 muM. Murine plasma samples (200 mul) were dilu ted up to a total volume of 500 mul with blank human plasma and the concent rations were read from the calibration curve prepared in human plasma. The lower limit of quantitation was 0.11 muM using 500 mul of human plasma and 0.28 muM using 200 mul of mouse plasma. The validation data showed that the assay is sensitive, selective and reproducible for determination of cyclos porin A. The applicability was demonstrated in a pharmacokinetic experiment where mice received oral cyclosporin A. (C) 2001 Elsevier Science B.V. All rights reserved.