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Guilherme Mazui

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What is the Difference Between Tacrolimus and Sirolimus?

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Tacrolimus and sirolimus are both immunosuppressive drugs used to prevent organ rejection in transplant patients, but they have some differences in their mechanisms of action, side effects, and clinical applications.

Tacrolimus is a calcineurin inhibitor, while sirolimus is an inhibitor of the mammalian target of rapamycin (mTOR). Both drugs are used in post-transplant therapy, but they have different side effect profiles and clinical outcomes.

Tacrolimus:

  • Commonly used as the most effective immunosuppressive drug after liver transplantation.
  • Known to cause nephrotoxicity, neurotoxicity, diabetes, hypertension, gastrointestinal disturbances, increased risk of infections, and malignancies.
  • May exert nephrotoxic and diabetogenic effects after simultaneous pancreas and kidney (SPK) transplantation.

Sirolimus:

  • Used in graft-versus-host disease (GVHD) prophylaxis regimens after allogeneic stem cell transplantation (SCT).
  • Associated with better survival in lung transplant patients compared to mycophenolate mofetil.
  • A randomized trial found no significant difference in kidney and pancreas graft survival at 1 and 5 years between sirolimus and tacrolimus groups.

Despite the noninferiority of sirolimus compared to tacrolimus for kidney and pancreas graft survival, the high rate of sirolimus discontinuation does not favor its use as cornerstone therapy after SPK transplantation. Physicians must be aware of the recent advances in tacrolimus and sirolimus therapies to make the best treatment decisions and improve patient outcomes.

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  • What is the Difference Between Tacrolimus and Sirolimus?
  • Comparative Table: Tacrolimus vs Sirolimus

    • Comparative Table: Tacrolimus vs Sirolimus

    Tacrolimus and sirolimus are both immunosuppressive drugs used in organ transplantation. Here is a table comparing their differences:

    Property Tacrolimus Sirolimus
    Origin Tacrolimus is derived from the fungus Streptomyces tsukubaensis. Sirolimus is a macrocyclic lactone immunosuppressive agent with a structure similar to tacrolimus.
    Mechanism of Action Tacrolimus is a calcineurin inhibitor that targets the T-cell signaling pathway. Sirolimus target the mammalian target of rapamycin (mTOR), an important regulator of cellular metabolism and growth.
    Acute GVHD Prophylaxis Tacrolimus can be used in combination with other immunosuppressive drugs for acute GVHD prophylaxis after reduced-intensity conditioning allogeneic peripheral blood stem cell transplantation (RIC SCT). A combination of sirolimus and tacrolimus can be used for acute GVHD prevention in patients undergoing RIC SCT.
    Administration Tacrolimus is administered orally at 0.05 mg/kg/day (in 2 daily divided doses) starting on day -3. Sirolimus is administered as an oral loading dose of 12 mg on day -3, followed by a 4 mg daily dose, adjusted to maintain a target serum concentration of 3-12 ng/mL.
    Withdrawal A study found that 34 patients (68%) in the sirolimus group needed definitive withdrawal of the study drug compared to three patients (6%) in the tacrolimus group. A study showed that a CNI-free regimen using sirolimus-MMF-prednisone produces similar acute rejection rates, graft survival, and renal function 1-2 years post-transplantation.

    In summary, tacrolimus and sirolimus are both immunosuppressive drugs, but they have different mechanisms of action and structures. Tacrolimus is a calcineurin inhibitor, while sirolimus targets mTOR. Both drugs can be used in combination with other immunosuppressive agents for acute GVHD prophylaxis after RIC SCT.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.