Tacsant 0.5mg Capsules Tacsant 0.5 mg contains Tacrolimus, a potent macrolide immunosuppressant derived from Streptomyces tsukubaensis. Tacrolimus acts by binding intracellularly to the immunophilin FK506-binding protein-12 (FKBP-12), forming a complex that inhibits calcineurin, a calcium-dependent phosphatase. This blockade prevents the dephosphorylation and nuclear translocation of the nuclear factor of activated T-cells (NFAT), suppressing the transcription of interleukin-2 (IL-2) and other cytokines necessary for T-lymphocyte activation and proliferation. Tacsant® 0.5 mg is indicated for the prophylaxis of organ rejection in allogeneic kidney, liver, or heart transplant recipients and for the treatment of allograft rejection resistant to other immunosuppressive regimens.