How does sirolimus contribute to immunosuppression following liver transplantation?

Updated: Dec 31, 2017
  • Author: Lemi Luu, MD, RDMS, FACEP, FAAEM; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Sirolimus is structurally related to tacrolimus, forming a complex with FK506 binding protein. However, it does not inhibit calcineurin as cyclosporine and tacrolimus do. The mechanism is not clear, but it appears to work by inhibiting IL-2 transduction and inducing the cell to arrest at the G1 to S phase of the cell cycle. Interestingly, sirolimus appears to have antitumorigenic effects through inhibition of angiogenesis. Studies are currently under way investigating this property.

It generally takes 3-5 days for serum levels of sirolimus to equilibrate, and often the sample must be sent out to specialized laboratories that are equipped to perform such studies.

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