Pharmacogenetic Trial of Tacrolimus After Pediatric Transplantation

Tacrolimus, a calcineurin inhibitor, is the commonest immunosuppressive agent used for maintenance immunosuppression after solid organ transplantation. The mechanism of action involves binding to an intracellular protein, FKBP-12. A complex of tacrolimus-FKBP-12, calcium, calmodulin and calcineurin is then formed and the phosphatase activity of calcineurin is inhibited. This prevents the generation of nuclear factor of activated T-cells, a nuclear component, resulting in inhibition of transcription of lymphokines (interleukin-2, γ-interferon). The net result is the inhibition of T-lymphocyte activation.Tacrolimus is metabolized primarily by the CYP3A enzymes in the liver particularly the CYP3A5.