Tacrolimus(FK506; FR900506) is a potent immunosuppressive drug often administered to transplant recipient patients and exhibits a variety of adverse cardiovascular effects.
IC50 Value: 0.47 nM (Inhibition of lymphocyte proliferation)
Target:
in vitro: MP and tacrolimus decreased the number of circulating helper-T cells with IC50 values of 23 ng/ml for MP and 6.7 ng/ml for tacrolimus. After coadministration of these drugs, an interaction occurs, but the nature (additive or antagonistic) of this interaction was not clear. The IC50 of tacrolimus for in vitro inhibition of lymphocyte proliferation was 0.39 ng/ml (0.47 nM) and 1.02 ng/ml (2.73 nM) for MP. The maximum percentage of inhibition was 94.6% for tacrolimus and 64.9% for MP. K506 inhibited the proliferation of T cell clones stimulated with specific antigens in a dose-dependent manner, and at about 100-fold lower concentrations than CsA. FK506 inhibited both IL-2 secretion and IL-2 receptor expression of BC.21 after stimulation with the specific antigen. FK506 also inhibited the proliferation of BC.21 stimulated with phorbol 12-myristate 13-acetate plus calcium ionophore.
in vivo:  Rat kidney TAC concentrations were higher (range 109-190 pg/mg tissue) than those in the liver (range 22-53 pg/mg of tissue), with median tissue/blood concentrations ratios of 72.0 and 17.6, respectively. In 2 transplant patients, kidney TAC concentrations ranged from 119 to 285 pg/mg of tissue and were approximately 20 times higher than whole blood trough TAC concentrations.
Clinical trial: PK Tacrolimus in Transplants. Phase 4

Polymyxin B sulphate
Telicoplanin
Tigecycline
Ascomycin
Calcipotriol
Pimecrolimus
Rapamycin/Sirolimus
Tacrolimus
Ramoplanin
Alvespimycin
Echinocandin B
Pristinamycin
Dibekacin sulphate
Arbekacin