Tacrolimus dose requirement in renal transplant recipients is significantly higher when used in combination with corticosteroids

Aims To evaluate the effect of corticosteroids on tacrolimus pharmacokinetics. Methods In a randomized trial, kidney transplant recipients were treated with tacrolimus and mycophenolate mofetil with either daclizumab (n = 31) or 3 months of prednisone (n = 34). Tacrolimus dose-adjusted predose concentrations (C,,) at month 1-6 were compared between both groups and within the corticosteroid group before and after prednisone withdrawal. Results At month 1 the tacrolimus dose-adjusted C-o in the corticosteroid group was 83 +/- 8 vs 119 +/- 17 ng ml(-1) mg(-1) kg(-1) in the daclizumab group. The tacrolimus dose-adjusted C-o within the corticosteroid group at month 1 and 2 was 42% and 29% lower compared with month 4 (P < 0.001). Conclusions A higher tacrolimus dose is required to reach target concentrations when used in combination with corticosteroids.