Everolimus and sirolimus in transplantation-related but different

Abstract

Introduction: The inhibitors of the mammalian target of rapamycin (mTOR) sirolimus and everolimus are used not only as immunosuppressants after organ transplantation in combination with calcineurin inhibitors (CNIs) but also as proliferation signal inhibitors coated on drug-eluting stents and in cancer therapy. Notwithstanding their related chemical structures, both have distinct pharmacokinetic, pharmacodynamic and toxicodynamic properties.

Areas covered: The additional hydroxyethyl group at the C(40) of the everolimus molecule results in different tissue and subcellular distribution, different affinities to active drug transporters and drug-metabolizing enzymes as well as differences in drug-target protein interactions including a much higher potency in terms of interacting with the mTOR complex 2 than sirolimus. Said mechanistic differences as well as differences found in clinical trials in transplant patients are reviewed.

Expert opinion: In comparison to sirolimus, everolimus has higher bioavailability, a shorter terminal half-life, different blood metabolite patterns, the potential to antagonize the negative effects of CNIs on neuronal and kidney cell metabolism (which sirolimus enhances), the ability to stimulate mitochondrial oxidation (which sirolimus inhibits) and to reduce vascular inflammation to a greater extent. A head-to-head, randomized trial comparing the safety and tolerability of these two mTOR inhibitors in solid organ transplant recipients is merited.

Keywords:

• comparison
• drug metabolism
• everolimus
• mitochondria
• mammalian target of rapamycin complex 2
• nephrotoxicity
• neuronal metabolism
• pharmacokinetics
• sirolimus
• vascular inflammation

Declaration of interest

B Nashan has received research funding and honoraria from Novartis Pharma and has served on Novartis Pharma advisory committees. J Klawitter and U Christianbs have received research funding from Novartis Pharma. The work was supported by United States National Institutes of Health grant R01HD70511 (UC). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents, received or pending, or royalties.

Notes

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