Drug concentration monitoring of immunosuppressive agents - Focus on tacrolimus, mycophenolate mofetil and sirolimus

Several new immunosuppressive agents have recently been approved for use in solid organ transplantation. Many of these agents have narrow therapeutic ranges, which necessitates drug concentration monitoring in order to optimise efficacy, minimise toxicity and individualise dosages, Some of the lessons learned with the clinical use of the revolutionary agent cyclosporin have been applied to the newer agents tacrolimus and sirolimus. The agent mycophenolate mofetil has been in clinical use without widespread drug concentration monitoring; however, recent data suggest that therapeutic monitoring may improve clinical outcomes, especially in certain high risk subsets of patients, This review focuses on the literature published to date on drug concentration monitoring of the newer immunosuppressive agents - tacrolimus, mycophenolate mofetil and sirolimus. In addition, pertinent aspects of the clinical pharmacokinetics and metabolism of each agent are reviewed.