

is difficult to single out in the early posttransplantation period. The Multidrug resistance gene 1 (MDR1) and CYP3A5 gene polymorphism may blend to achieve the optimal level. A narrow therapeutic index, multiple drug interactions, and interindividual variability in pharmacokinetics make it obligatory to monitor therapeutic drug levels. Tacrolimus (TAC) is the mainstay immunosuppressant for renal transplantation.
