Single daily high-dose mizoribine therapy for children with steroid-dependent nephrotic syndrome prior to cyclosporine administration.

Although cyclosporine (CsA) therapy is effective in the management of children with steroid-dependent nephrotic syndrome (SDNS), a recent study has revealed that the use of CsA itself was a significant predictor of NS relapse in adulthood. The efficacy of single daily high-dose mizoribine (MZR) therapy was assessed in 10 children with SDNS (mean age, 6.2 years) who had never been treated with CsA previously. MZR was started at 5 mg/kg, administered as a single daily dose after breakfast, and the dose was adjusted to achieve 2-h post-dose MZR levels (C2) of approximately 3 μg/ml. In 9 of the 10 patients, treatment with a single daily dose of MZR (mean dose, 8.4 mg/kg/day) over a period of 22 months (median) resulted in significant reduction of the mean prednisolone dose from 0.39 to 0.15 mg/kg/day and the median 12-month relapse rate from 3.0 to 0.4 episodes/12 months. Although cyclophosphamide was initiated in one patient because of treatment failure, none of the 10 patients required treatment with CsA during the observation period (median, 33 months). These data indicate that single daily high-dose MZR therapy is possibly useful in treating children with SDNS and that it may also eliminate the need for CsA in some patients.