Tacrolimus is an immunosuppressant drug, and acts as a calcineurin inhibitor (CNI) in which it blocks T-cell transcription processes required for production of cytokines, thereby selectively inhibiting T-cell proliferation and activation. Tacrolimus is the most commonly used drug in kidney, liver, pancreas, and small-bowel transplantation. It may be started at the time of transplantation or days after the procedure. Adverse effects of Tacrolimus are similar to those of cyclosporine except Tacrolimus is more prone to induce diabetes. It may also cause hypertension, tremor, and increased creatinine levels. The tacrolimus test is ordered to measure the amount of drug in the blood to determine whether concentrations have reached therapeutic levels and is below toxic levels.
Trough levels should be drawn 12 Hrs post-dose.