Experience with cyclosporine: approaching the therapeutic window for C2 levels in maintenance kidney transplant recipients

This study was aimed to evaluate the clinical benefit of C-2 monitoring in 191 stable renal transplant patients previously monitored by C-0. All patients had been transplanted for at least 1 year and received cyclosporine (CsA)-based immunosuppression since the start. At the inceptions C-0 levels were significantly correlated with C-2 values (P < .0001). Patients with starting C-2 levels >1000 ng/mL showed significantly higher levels of serum creatinine (sCr) both at inception (1.66 +/- 0.50 vs 1.44 +/- 0.41 mg/dL; P =.0021) and at the end of a 2-year follow-up (1.84 +/- 0.80 vs 1.46 +/- 0.51 mg/dL; P = .005). C-2 monitoring revealed that a high percentage of patients were overexposed to CsA, mainly in the subgroup with most recent renal engraftments (12 to 24 months). The switch to C-2 monitoring was associated with a slower deterioration of graft function (P = .02). Further, the mean values of C-2 over a 2-year follow-up were inversely correlated with sCr at the end of follow-up (P = .0005). Finally, patients with mean threshold C-2 levels above 720 ng/mL, roughly corresponding to the median value of C-2, showed significantly lower levels of sCr at the end of follow-up (P = .0004). In conclusion, C-2 monitoring of maintenance renal transplant patients allows one to identify a significant percentage of overexposed subjects, possibly limiting the rate of progression of chronic graft dysfunction. Target range values between 700 and 900 ng/mL appear to be associated with better long-term kidney graft function.