Measurement of Tacrolimus: A Review of Laboratory Methods

Abstract

Tacrolimus is an immunosuppressive agent prescribed in various medical conditions like organ transplantation, malignancies, autoimmune diseases, and for the treatment of Nephrotic Syndrome. It has a narrow therapeutic index and even at a low trough level (4-6 ng/mL) has been found to be linked with nephrotoxicity. Therapeutic drug monitoring of immunosuppressive drugs is required because of their varied metabolism, absorption, and drug interactions. The pharmacokinetics data of Tacrolimus is also very limited for the treatment of steroid resistant nephrotic syndrome in children. There are various laboratory detection methods which have an important role in treatment outcomes. Aim of this study is to review various laboratory methods in terms of functional feasibility, cost-effectiveness, and turnaround time (TAT) for therapeutic drug monitoring of tacrolimus. Published data of various laboratory detection methods have been evaluated in this study and found that LC-MS and Immunoassay are two important techniques that are applied for the therapeutic monitoring of Tacrolimus. The LC-MS is a gold standard method that requires a high degree of technical competence and extensive training to perform therapeutic drug testing. Turbidimetric immunoassays can also be an alternative to LC-MS in resource-constraint laboratory facilities.