Calcineurin inhibitors tacrolimus

Griseofulvin, lAA, podophyllotoxin, taxol, vinblastine, vincristine Calcineurin inhibitors tacrolimus, cyclosporin A... 

The calcineurin inhibitors tacrolimus (FK 506) and cyclosporin A block the function of dynamin and are thought to be specific for clathrin-mediated uptake (50). The smal guanosine triphosphate (GTP)ase dynamin is also involved in other processes and is therefore described in section Dynamin Dependence on Liposome Uptake. ... 

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterised by extreme pruritus and lichenified papules and plaques that may begin in or persist in to adulthood. Topical corticosteroids are first-line prescription therapy for AD they are efficacious and have a well established safety profile. The topical calcineurin inhibitors tacrolimus and pimecrolimus have been approved as second-line topical therapy for AD. The current review evaluates the available studies on the comparative effectiveness, safety, cost, and impact on quality of life of topical corticosteroids and topical calcineurin inhibitors for the treatment of adult AD [17 ]. 

Cyclosporine and tacrolimus are calcineurin inhibitors that are administered as part of immunosuppressive regimens in kidney, liver, heart, lung, and bone marrow transplant recipients. In addition, they are used in autoimmune disorders such as psoriasis and multiple sclerosis. The pathophysiologic mechanism for ARF is renal vascular vasoconstriction.41 It often occurs within the first 6 to 12 months of treatment, and can be reversible with dose reduction or drug discontinuation. Risk factors include high dose, elevated trough blood concentrations, increased age, and concomitant therapy with other nephrotoxic drugs.41 Cyclosporine and tacrolimus are extensively metabolized by... 

The calcineurin inhibitors cyclosporine and tacrolimus block T cell activation by inhibiting the production of IL-2. They are associated with significant adverse events, such as nephrotoxicity, cardiovascular disease, posttransplant diabetes, and neurotoxicity. 

Cyclosporine and tacrolimus belong to a class of immunosuppressants called the calcineurin inhibitors. These agents are considered by many to be the cornerstone of medical immunosuppression. The calcineurin inhibitors work by complexingwith cytoplasmic proteins (cyclosporine with cyclophylin and tacrolimus with FK binding protein 12). These complexes then inhibit calcineurin phosphatase, which results in reduced IL-2 gene transcription. The final outcome is a decrease in IL-2 synthesis and a subsequent reduction in T cell activation.7 11 20 21... 

FIGURE 52-2. Center-specific protocols may use RATG, an IL-2RA, or no induction therapy. In any situation, patients receive IV methylprednisolone prior to, during, or immediately following the transplant operation. The patient then will begin the maintenance immunosuppressive regimen. The center-specific protocol will specify which calcineurin inhibitor (cyclosporine or tacrolimus) is used in combination with mycophenolate mofetil or sirolimus with or without steroids. Patients then are monitored for signs and symptoms of rejection. 

Sirolimus is currently the only FDA-approved ToR inhibitor. One of its derivatives, everolimus, is in phase III clinical trials and has been approved for use in some European countries.30 Sirolimus is a macrolide antibiotic that has no effect on cal-cineurin phosphatase.11,31,32 Sirolimus inhibits T cell activation and proliferation by binding to and inhibiting the activation of the mammalian ToR, which suppresses cellular response to IL-2 and other cytokines (i.e., IL-4 and IL-15J.11,31 Studies have shown that sirolimus may be used safely and effectively with either cyclosporine or tacrolimus as a replacement for either azathioprine or mycophenolate mofetil.33 However, when using both sirolimus and cyclosporine as part of a patient s immunosuppressant therapy, because of a drug interaction between the two resulting in a marked increase in sirolimus concentrations, it is recommended to separate the sirolimus and cyclosporine doses by at least 4 hours. Sirolimus also can be used as an alternative agent for patients who do not tolerate calcineurin inhibitors due to nephrotoxicity or other adverse events.34... 

Although tacrolimus therapy is associated with increasing blood pressure, studies have found that tacrolimus has less dramatic effects on GFR and RBF than cyclosporine. In some clinical trials, tacrolimus caused less severe HTN and required significantly fewer antihypertensive medications at both 24 and 60 months after transplantation than cyclosporine.61-63 Thus conversion from cyclosporine-based immunosuppression to tacrolimus-based immunosuppression may be one way to minimize blood pressure increases in transplant recipients. Conversion to sirolimus also may be an alternative to the calcineurin inhibitors in patients with difficult-to-treat HTN because sirolimus therapy is less associated with increased blood pressure. Additionally, withdrawal or tapering of steroid therapy may be an effective strategy for lowering blood pressure. 

ACE inhibitors and angiotensin-receptor blockers (ARB) have definite benefits in patients with nephropathy and are believed to have renoprotective effects in most patients. Due to their ability to cause an initial bump in serum creatinine, these agents should be used cautiously when employed in combination with the calcineurin inhibitors. The dihydropyridine calcium channel blockers have demonstrated an ability to reverse the nephrotoxicity associated with cyclosporine and tacrolimus (Table 52-8). In general, antihypertensive therapy should focus on agents with proven benefit in reducing the progression of cardiovascular disease and should be chosen on a patient-specific basis.55 See Chapter 2 for further recommendations for treating HTN. 

Topical calcineurin inhibitors (e.g., tacrolimus ointment, pimecrolimus cream) have fungicidal and antiinflammatory properties and can be used for the scalp or face. 

After transplantation, immunosuppression must be used to prevent host rejection of the graft liver, usually with prednisone and tacrolimus or cyclosporine. Tacrolimus and cyclosporine are calcineurin inhibitors and require drug level monitoring because of a narrow therapeutic range and significant toxicity, including renal failure and neurotoxicity. 

In most patients who develop CRF, renal transplantation from cadaver donors or living related donors is desirable. Post-transplant immuno-suppression with calcineurin inhibitors (e.g. cyclosporin, tacrolimus), anti-proliferative agents (e.g. azathioprine, myco-phenolate mofetil) and steroids (prednisolone), singly or in combination, are required. It has been... 

Toxicities of the PSIs can include profound myelosuppression (especially thrombocytopenia), hepatotoxicity, diarrhea, hypertriglyceridemia, pneumonitis, and headache. Because nephrotoxicity is of major concern when administering calcineurin inhibitors, there is interest in increased early use of PSIs since renal toxicity is less common with these agents. However, increased use in stem cell transplantation regimens as graft-versus-host disease prophylaxis, particularly when combined with tacrolimus, has revealed an increased incidence of hemolytic-uremic syndrome. 

The metabolism of mycophenolate is altered by coadministration with cyclosporine. Mycophenolic acid (MPA) levels are lower when mycophenolate mofetil is compared with cyclosporine. Lower doses should be considered in recipients receiving tacrolimus or steroids done without a calcineurin inhibitor. 

Sirolimus is used for tissue transplantation where its major advantage over calci-neurin inhibitors is that it is not nephrotoxic. Chronic renal failure in transplant patients who have taken calcineurin inhibitors for the long term can be prevented by the administration of sirolimus. Steroid-free immunosuppression can be achieved by administering sirolimus alone or in combination with mycophenolate mofetil and cyclosporine or tacrolimus. Since impaired wound healing is one of its potential side effects, some transplant centers use sirolimus only after several weeks of surgery. 

The effect was observed in those with renal transplants (9.8% versus 2.7%) and those with other organ transplants (11.1% versus 6.2%), and among patients who were taking equal doses of concomitant medications in both treatment arms (12% versus 3%). Further factors associated with diabetes mellitus after kidney transplantation were older recipient age, a cadaveric organ, hepatitis C antibody status, an episode of rejection, and the use of tacrolimus (versus ciclosporin) cumulative glucocorticoid dose and calcineurin inhibitor trough concentration were not associated factors (1100). 

Mechanism of Action. Cyclosporine and tacrolimus (see below) are known as calcineurin inhibitors because they inhibit a specific protein (calcineurin) in lymphoid tissues. This inhibition ultimately suppresses the production of IL-2, a cytokine that plays a critical role in immune response by promoting the growth and proliferation of activated T lymphocytes and other immune cells, such as NK. cells (see Fig. 37—1).5,52 Thus, cyclosporine is one of the premier immunosuppressants because of its relative selectivity for T cells and its inhibition of a key mediator of the immune response (IL-2).41 This relatively specific inhibition is often advantageous when compared with other nonse-lective drugs such as azathioprine, cyclophosphamide, and glucocorticoids that inhibit virtually all the cells and chemical mediators involved in the immune response. 

Antibodies that block the interleukin-2 receptor, thus preventing interleukin-2 from activating T lymphocytes, have also been developed.24,62 These antiinterleukin-2 receptor agents, such as basiliximab (Simulect) and daclizumab (Zenapax), may be helpful in reducing the incidence of acute transplant rejection.13 Antibodies seem to be especially useful in the initial (induction) phase of antirejection treatment because these drugs can delay or supplant the use of more toxic immunosuppressants such as the glucocorticoids and calcineurin inhibitors (cyclosporine and tacrolimus).3,56... 

Topical calcineurin inhibitors (e.g., tacrolimus ointment, pimecrolimus... 

Topical calcineurin inhibitors are also used to treat atopic dermatitis and include pimecrolimus (Elidel) and tacrolimus (Protopic).Treatment effects are seen in 1 to 3 weeks. Adverse reactions most commonly include burning. Although a causal relation has not been established, rare skin malignancy and lymphoma have been reported. 

Sirohmus is a macrocychc lactone produced by the bacteria Streptomyces hygroscopious. Like the calcineurin inhibitors cyclosporine and tacrolimus its mechanism of action involves formation of a complex with an immunophiUn, in this case, FKBP-12. Unlike cyclosporine and tacrolimus, sirohmus does not affect calcineurin activity but binds to and inhibits the mammalian kinase, target of rapamycin (mTOR.). mTOR is a key enzyme in cell-cycle progression. When inhibited this kinase blocks cell cycle progression at the G1 to S phase transition (Dumont and Su, 1996 Sehgal, 2003). 

Calcineurin inhibitors ciclosporin, everolimus, pimecrolimus, sirolimus, tacrolimus, temsirolimus. 

Drugs such as cyclosporine and tacrolimus, belong to a class of commonly used immunsuppressants for organ transplantation referred to as calcineurin inhibitors. Calcineurin inhibitors are associated with... 

Immunosuppressive drugs can be divided into five basic categories. Corticosteroids such as methylprednisolone and prednisone are a part of virtually all immunosuppressive drug regimens. Corticosteroids block the production of IL-1 and have potent anti-inflammatory effects. Calcineurin inhibitors such as cyclosporine and tacrolimus are also used in a majority of immunosuppressive drug regimens. Calcineurin inhibitors inhibit the production and secretion of IL-2. IL-2 is involved with T-lymphocyte activation and proliferation. Antiproliferative agents such as azathioprine, mycophenolate mofetil, and sirolimus block T-lymphocyte... 

The calcineurin inhibitors (cyclosporine and tacrolimus) and sirolimus are metabolized in the liver and gut by CYP450-... 

There are numerous case reports where patients on a calcineurin inhibitor, such as cyclosporine or tacrolimus, began taking St. John s wort and developed significant reductions in plasma concentrations of the drugs (74-81). Both cyclosporine and tacrolimus are metabolized by the CYP3A4 enzyme system, and cyclosporine is also a substrate of Pgp (74,81). There are reports of acute graft rejections caused by low cyclosporine or tacrolimus serum concentrations in heart, liver, and kidney transplant recipients who were taking St. John s wort (75,76). 

Hesselink DA, van Schaik RH, van der Heiden IP, van der Werf M, Gregoor PJ, Lindemans J, Weimar W, van Gelder T (2003) Genetic polymorphisms of the CYP3A4, CYP3A5, and MDR-1 genes and pharmacokinetics of the calcineurin inhibitors cyclosporine and tacrolimus. Clin Pharmacol Ther 74 245-254... 

Induction therapy involves the use of a high level of immunosuppression at the time of transplantation with or without the immediate introduction of cyclosporine or tacrolimus (see Fig. 87-2). While induction historically consisted of the use of polyclonal or monoclonal antibodies in addition to triple therapy of azathioprine, high-dose corticosteroids, and a calcineurin inhibitor (e.g., cyclosporine... 

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