Tacrolimus

Tacrolimus (also FK-506 or Fujimycin) is an immunosuppressive drug whose main use is after organ transplant to reduce the activity of the patient's immune system and so the risk of organ rejection. It is also used in a topical preparation in the treatment of severe atopic dermatitis, severe refractory uveitis after bone marrow transplants, and the skin condition vitiligo. It was discovered in 1984 from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis. Tacrolimus is chemically known as a macrolide. It reduces peptidyl-prolyl isomerase activity by binding to the immunophilin FKBP-12 (FK506 binding protein) creating a new complex. This FKBP12-FK506 complex inhibits calcineurin which inhibits T-lymphocyte signal transduction and IL-2 transcription.

Immediate-release formulations of tacrolimus are indicated for the prophylaxis of organ rejection in adult and pediatric patients receiving allogeneic liver, kidney, heart, or lung transplants, in combination with other immunosuppressants. Extended-release formulations of tacrolimus are indicated for the prophylaxis of organ rejection in adult and pediatric patients receiving kidney transplants, in combination with other immunosuppressants, and may be used in patients converted from immediate-release formulations.

Topical tacrolimus ointment is indicated as second-line therapy for short-term and non-continuous treatment of moderate-to-severe atopic dermatitis in non-immunocompromised adults and children who have failed to respond adequately to other topical treatments or for whom alternative treatments are not advisable. Both available strengths are indicated in adult patients, while only the lower strength (0.03%) formulation is indicated in pediatric patients between 2 and 15 years of age.