Is C2 monitoring or another limited sampling strategy superior to C0 monitoring in improving clinical outcomes in adult liver transplant recipients?

Cyclosporine (CsA) has had a major impact on the process and success of solid organ transplantation. Early in the use of CsA, therapeutic monitoring using the predose (trough, or C0) concentration became the standard of care. However, there are complications with the use of C0 monitoring that have only partly been mitigated with the advent of the micro-emulsion formulation (CsA-ME). More recently, limited sampling strategies (LSSs) for measuring the area under the CsA concentration-time curve (AUC) have been investigated to improve the monitoring of CsA post-transplantation. Many centres now routinely monitor CsA therapy using the concentration at 2 hours postdose (C2). In this paper the strength of the evidence for C2 (or other LSSs) relative to C0 monitoring of CsA-ME for improving clinically important outcomes in liver transplant patients is critically examined. Additionally, gaps in the literature are identified and recommendations are made for clinical research that could be done to provide more definitive evidence for the use of C2 or other LSSs in monitoring liver transplant patients.