Therapeutic monitoring of cyclosporine in kidney transplantation: the Halifax experience.

Appropriate dosing of an immunosuppressive agent is critical to its efficacy and tolerability. Finding a simple and effective method of monitoring cyclosporine (CsA/CyA) has been formidable despite a long history of widespread usage. Earlier reports linked CsA dosing to trough levels (C0), whereas later more elaborate systems have evaluated efficacy linked to 12-hour area-under-the-curve (AUC(0-12)) as a measure of total drug exposure. Recent work done at our center and elsewhere has shown that the 2-hour postdose concentration (C2) to be simple and more effective than the C0 or the AUC. With C2 monitoring as a guide to CsA dosing, acute rejection (AR) and nephrotoxicity (NT) can be effectively reduced. Furthermore, absorption profile as per C2 levels further emphasizes the importance of achieving the targeted peak concentration in the first week of transplantation. The C2 concentration strategy is discussed in light of newer induction agents and other immunosuppression.