How long has prograf been around for transplant patients?

Widely since 1994. Prograf or tacrolimus or fk-506 is a 23-membered macrolide lactone discovered in 1984 from the fermentation broth of a japanese soil sample that contained the bacteria streptomyces tsukubaensis. It was approved by the fda as an immunosuppressant for liver transplanation in 1994 and is now approved for all solid organ transplants.
Over 20 years . Trials of the drug in the us started in the late 80s. It was fda approved for kidney transplant in the 1990s.