Definition

Tacrolimus belongs to a group of medicines known as immunosuppressive agents. It is used primarily to lower the body's natural immunity in order to prevent the rejection of organ transplants and to prevent graft-versus-host disease. Tacrolimus is also known as Prograf and FK506.

Purpose

Tacrolimus first saw use in transplant patients. By suppressing the activity of the immune system, tacrolimus makes it more likely that the recipient of a transplanted organ will accept that organ. It is especially used for kidney transplants.

In the fight against leukemia, grafts of stem cells from donors are sometimes given to the patient to encourage the blood of a recipient to begin production of normal cells. Tacrolimus may be given during the graft process because it...