Calcineurin inhibitors, such as cyclosporine and tacrolimus, have improved allograft survival in kidney organ transplantation. Indeed, they have reduced the incidence of acute rejection episodes of cadaveric allograft recipients. Although marked progression has been made in initial survival rates, long-term kidney graft survival has yet to show such encouraging results. Because CNIs are associated with adverse effects, particularly nephrotoxicity, which contribute to declining organ function and eventual graft loss. In kidney transplants, progressive allograft dysfunction has been shown to develop in as many as 94% of patients by 1 year.