Description: Sirolimus, also known as rapamycin, is an immunosuppressant drug. It is a macrolide produced by the bacterium Streptomyces hygroscopicus.

Indication:

• Renal Transplant: Primarily used for the prophylaxis of organ rejection in patients receiving a kidney transplant.
• Lymphangioleiomyomatosis (LAM): Approved to treat LAM, a rare, progressive lung disease.
• Certain Tumors: Investigated for use in some types of cancer.

Mechanism of Action: Sirolimus works by inhibiting the mammalian target of rapamycin (mTOR), a protein that regulates cell growth, proliferation, and survival. By blocking mTOR, sirolimus prevents the activation of T-cells and B-cells, which are essential components of the immune system responsible for attacking foreign substances and transplanted organs. This action suppresses the immune response, helping to prevent organ rejection.