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 C2 monitoring in 191 stable renal transplant patients previously monitored by C0. All patients had been transplanted for at least 1 year and received cyclosporine (CsA)-based immunosuppression since the start. At the inceptions C0 levels were significantly correlated with C2 values (P<.0001). Patients with starting C2 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). C2 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 C2 monitoring was associated with a slower deterioration of graft function (P=.02). Further, the mean values of C2 over a 2-year follow-up were inversely correlated with sCr at the end of follow-up (P=.0005). Finally, patients with mean threshold C2 levels above 720 ng/mL, roughly corresponding to the median value of C2, showed significantly lower levels of sCr at the end of follow-up (P=.0004). In conclusion, C2 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.