ANALYSIS OF WHOLE-BLOOD CYCLOSPORINE-G BY LIQUID-CHROMATOGRAPHY IN RENAL-TRANSPLANT RECIPIENTS

Cyclosporin G (CsG) is less nephrotoxic than Cyclosporin A (CsA) and i s undergoing clinical trials for use as an immunosuppressive agent aft er renal transplantation. In this study, CsG was measured by a rapid h igh-performance liquid chromatography (HPLC) technique in blood sample s (n = 107) received from renal transplant recipients. The HPLC assay proved to be analytically suitable in that it was sensitive, linear, a nd precise and had high recovery (102%). However, interference was obs erved from some potentially co-administered drugs such as calcitriol, ferrous sulfate, hydrazaline, and minoxidil. The HPLC assay for CsG co rrelated well with a FPIA (Abbott TDx), FPIA = 0.964 (HPLC) + 33.59, r = 0.9819, S-y/x = 36.66 for patients receiving a low dose of CsG (5 m g/kg/day) and a high dose (10 mg/kg/). Furthermore, the HPLC technique was capable or measuring predictable CsG concentrations when the drug was tapered to lower doses at various stages of the 16 week clinical trial. The HPLC for CsG has the further advantage that the same system and mobile phase can be used to measure CsA while using CsC as the in terval standard. (C) 1995 Wiley-Liss, Inc.