FK506

Mechanism of action

In detail, tacrolimus reduces peptidylprolyl isomerase activity by binding to the immunophilinFKBP12 (FK506 binding protein), creating a new complex. This FKBP12–FK506 complex interacts with and inhibits calcineurin, thus inhibiting both T lymphocyte signal transduction and IL-2 transcription. Although this activity is similar to that of cyclosporin, the incidence of acute rejection is reduced by tacrolimus use over cyclosporin use. Although short-term immunosuppression concerning patient and graft survival is found to be similar between the two drugs, tacrolimus results in a more favorable lipid profile, and this may have important long-term implications given the prognostic influence of rejection on graft survival.