A TACROLIMUS LEVEL TEST MEASURES THE CONCENTRATION OF THE DRUG TACROLIMUS IN THE BLOOD. TACROLIMUS IS A POWERFUL IMMUNOSUPPRESSANT MEDICATION USED PRIMARILY TO PREVENT THE REJECTION OF TRANSPLANTED ORGANS (SUCH AS KIDNEYS, LIVER, AND HEART).

SIROLIMUS IS AN IMMUNOSUPPRESSANT DRUG USED EITHER IN ADDITION TO CYCLOSPORINE OR TACROLIMUS OR AS A SUBSTITUTE IN PATIENTS INTOLERANT TO THESE DRUGS. THIS ASSAY MONITORS SIROLIMUS CONCENTRATION DURING THERAPY PARTICULARLY IN INDIVIDUALS CO-ADMINISTERED CYP3A4 SUBSTRATES, INHIBITORS OR INDUCERS. THE ASSAY HELPS TO EVALUATE PATIENT COMPLIANCE, ADJUST DOSE TO OPTIMIZE IMMUNOSUPPRESSION WHILE MINIMIZING TOXICITY.