Optimization of cyclosporine for liver transplantation.

Our understanding of cyclosporine (CsA) administration for liver transplantation has significantly improved over the past decade. Cyclosporine is a highly lipophilic molecule, and the original galenic formulation, Sandimmune, was highly dependent on bile flow and gut motility for its absorption. Sandimmune's poor absorption profile produced erratic CsA levels after liver transplantation. A new microemulsification formulation of CsA, Neoral (CsA-ME), was developed to overcome these limitations. The NOF-1 study confirmed the superiority of CsA-ME's absorption compared with Sandimmune; CsA-ME had a more consistent and reliable absorption, with lower intrapatient variability and improved dose linearity with drug exposure as measured by area under the concentration-time curve (AUC). These advantages translated into more reliable CsA predose concentrations and less toxicity. An analysis of the pharmacokinetic data showed that 2-hour postdose CsA levels (C2) provided a better measure of immune suppression than did trough levels (C0). The LIS2T study recently confirmed and extended these data by showing equivalent efficacy between CsA-ME using C2 monitoring or tacrolimus in liver transplant patients, with a similar incidence of adverse events except for a higher rate of diabetes mellitus and diarrhea with tacrolimus. These data confirmed that the improved CsA-ME formulation, when used in conjunction with optimized drug-monitoring protocols, is well tolerated after transplantation and provides low rates of graft rejection.