Risk factors of cyclosporine nephrotoxicity after conversion from Sandimmune to Neoral.

BACKGROUND In 1995 - 1996, we switched from a once-daily Sandimmune dose to a twice-daily dose regimen of Neoral. Concurrent with the switch we changed our target trough level from 100 microg/l at 24 hours to the generally accepted 12-hour level of 150 microg/l. We performed a retrospective cohort study to assess cyclosporine toxicity following this switch and to identify risk factors for nephrotoxicity. PATIENTS AND METHODS Of 212 patients with a stable graft function pre-conversion clinical parameters at 1 and 12 months post-conversion were compared with those at time of conversion. Cyclosporine nephrotoxicity was defined as a significant decline of the reciprocal of the serum creatinine concentration over time post-conversion in the absence of other obvious causes for declining graft function. Risk factors of cyclosporine nephrotoxicity were assessed using logistic regression analysis. RESULTS The mean cyclosporine trough level rose from 87 microg/l at the time of conversion to 139 microg/l at 12 months post-conversion whereas the daily drug dose increased over the same period from 233 mg to 252 mg. Mean serum creatinine increased by 10% from 135 to 148 micromol/l (p < 0.001). Cyclosporine nephrotoxicity was present in 42 patients (20%). Cyclosporine dose and trough level did not predict nephrotoxicity but beta-blockers (OR 0.35, 95% CI 0.17-0.72) and calcium channel blockers (OR 0.35, 95% CI 0.19-0.82) reduced the risk of nephrotoxicity, independent from an effect on blood pressure. CONCLUSION 20% of stable renal transplant patients experienced chronic cyclosporine nephrotoxicity after conversion from a once-daily Sandimmune regimen to a twice-daily Neoral regimen with dose adjustments to a trough level of 150 microg/l. beta-blockers and calcium channel blockers reduced the risk of nephrotoxicity.