Preservation of renal function during maintenance therapy with cyclosporine

During the last 20 years the management of cyclosporine (CsA) has improved due to the introduction of microemulsion technology, C2 monitoring, and combination with other new immunosuppressants. All these modifications have reduced the incidence of biopsy-proven acute rejection episodes to approximately 10%. However despite the wide experience, there are unanswered questions regarding CsA monitoring after the first year. Available clinical and histological data suggest that the therapeutic range to avoid nephrotoxicity or underimmunosuppression during the maintenance period is rather narrow. Furthermore, the combination of CsA with new immunosuppressants may modify the target CsA levels. Although the utility of C2 levels during the first year has been well characterized, there are few data on its utility for maintenance therapy, particularly the therapeutic range for C2 levels in patients receiving different immunosuppressive combinations. Since serum creatinine does not precisely reflect the progression of chronic allograft nephropathy, the efficacy of C2 monitoring during the maintenance period must be assessed not only by means of evaluation of renal function, but also histologic assessment using protocol biopsies.