Background: Cyclosporin A (CsA) concentration monitoring with 2 h post-dosing levels (C2) correlates with the incidence of rejection and graft outcome in de novo renal transplant patients. The advantages of this policy beyond the first 12 months remain a matter of debate. The purpose of the present work was to evaluate the C2 target ranges on CsA monitoring after the first year in stable kidney transplant patients.
Methods: We studied 142 patients, 94 on CsA-steroids and 48 on triple therapy (CsA-azathioprin-steroids), transplanted for 104+/-42 months and with a serum creatinine of 1.53+/-0.52 mg/dl. C2 and C0 measurements were performed at baseline and at least twice more during the year of follow-up.
Results: The mean annual C2 blood levels in double therapy patients showed C2 in 23 (24.5%) of <600 ng/ml; in 53 (56.4%) of between 600 and 850 ng/ml; and in 18 patients (19.1%) of >850 ng/ml. In the triple therapy group, C2 in 12 (25%) was <500 ng/ml, in 24 (50%) between 500 and 700 ng/ml and in 12 patients (25%) >700 ng/ml. In both groups, higher C2 levels were associated with a better absorption of the drug measured by the ratio C2/C0 and C2/dose. There were no differences in incidence of infections, need for hospitalization and the presence of hypertension, hyperuricaemia, hypercholesterolaemia or diabetes between patients with low and high C2 blood levels. However, serum creatinine was higher in triple therapy patients with lower C0 levels (P = 0.004). In 135 patients (90 on double and 45 on triple therapy), renal function remained stable during follow-up and 120 of them (89%) had C2 values under the recommended ranges.
Conclusions: C2 monitoring in maintenance patients enabled us to identify overexposure to CsA. Target levels of C2 should be adjusted according to the immunosuppressive regime. C2 levels between 600 and 800 ng/ml in double therapy patients and between 500 and 700 ng/ml in triple therapy patients are sufficient to give an adequate immunosuppression. The superiority of C2 with respect to C0 levels could not be demonstrated.