Sirolimus (INN/USAN), also known as rapamycin, is an immunosuppressant drug used to prevent rejection in organ transplantation; it's especially useful in kidney transplants. A macrolide, sirolimus was first discovered as a product of the bacterium Streptomyces hygroscopicus in a soil sample from Easter Island — an island also known as "Rapa Nui", hence the name. It is marketed under the trade name Rapamune by Wyeth. Sirolimus was originally developed as an antifungal agent. However, this… (More on Sirolimus)