Background. A microemulsion formulation of cyclosporine, Neoral, has been developed to overcome the problems associated with the poor and variable absorption of the traditional oil-based oral formulation, Sandimmune. The present study was conducted to compare the safety and tolerability of Neoral versus Sandimmune in maintenance renal transplant recipients over 1 year, and to assess the number of dose adjustments necessary to maintain trough cyclosporine concentrations within the desired therapeutic range. Methods. Patients on Sandimmune were randomized to be converted to Neoral (n=373) or remain on Sandimmune (n=93) for 12 months. Results. The proportion of patients needing dose increases to mAintAin cyclosporine trough levels within the desired range was significantly higher in the Sandimmune group during the first 3 months of the study, whereas the number of patients needing dose reductions was similar in both groups throughout the study period. There were no differences between the groups in terms of changes in blood pressure, serum creatinine levels, or other laboratory parameters. No significant differences in the incidence of adverse events known to be related to cyclosporine were observed between the treatment groups. Moro adverse events were causally related to Neoral than to Sandimmune by the investigators. However, overall, there were no clinically relevant differences between the treatment groups in the main safety and tolerability variables. Conclusions. The results of this study in maintenance renal transplant patients suggest that the improved pharmacokinetic characteristics of the microemulsion formulation of cyclosporine, Neoral, may facilitate the clinical management of cyclosporine immunosuppression, compared with the traditional formulation, Sandimmune. Furthermore, there is no evidence that the average improved bioavailability of Neoral has a negative impact on the main safety and tolerability variables, as no significant differences in graft function, the incidence of rejections, and most adverse events were seen.
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