Introduction
Cyclosporin A (CsA) is a cyclic polypeptide consisting of 11 amino acids, which contains a new amino acid containing 9 carbons with an ethylene double bond, and is widely used as a second generation immunosuppressant. CsA can inhibit the production of T lymphocytes by controlling the production of IL-2, and the inhibition of T lymphocytes will weaken the immune rejection of the body. CsA is an effective immunosuppressant and is worthy of clinical application.
Pharmacologic action
Cyclosporin A forms a complex with cyclophilins (CyP) and interacts with calcium/calcium -binding protein-dependent calcineurin (CaN) to inhibit NF-AT (nuclear factors of activated T cell). Dephosphorylation of nuclear factor prevents it from entering the nucleus, and thereby the production of IL-2 is inhibited, and the production of T lymphocytes is inhibited. There are two main reasons for the inhibition of IL-2. On the one hand, CsA inhibits the production of IL-2, which is most sensitive to its inhibition. Due to the inhibition of IL-2 production, cytotoxic T lymphocytes are vegetatively propagated. Cytotoxic T lymphocyte asexual reproduction cell proliferation is also inhibited and the inhibitory concentration is 10-20 ng. In addition, CsA can inhibit the immune response of cytotoxic T lymphocytes to IL-2 by inhibiting the production of IL-2 receptor, and its inhibitory concentration is about 100 ng·mL.
Function
Cyclosporin A has an immunosuppressive effect and can improve the anti-rejection reaction during organ transplantation. It is capable of treating graft-versus-host disease (GVHD), and it is also the most widely used in kidney transplantation. CsA can improve the abnormal phenomenon of T lymphocytes and limit the production of negative blood negative regulators. Therefore, it is an effective drug for the treatment of aplastic anemia (AA). CsA can treat nephrotic syndrome mainly by increasing the pore size selectivity and charge selectivity of the glomerular basement membrane to reduce the production and elimination of proteinuria. Moreover, CsA has a synthetic effect on the inhibition of rheumatoid synovial membrane production, such as interleukin (IL21, IL26) and tumor necrosis factor (TNF), so it can be used for the treatment of rheumatoid arthritis.
Pharmacokinetics and metabolism
CsA has high lipophilicity and large differences in oral bioavailability and elimination half-life, and its oral bioavailability is 8% to 60%. The peak drug concentration in blood appears 1 to 8 hours after administration. CsA is widely distributed in the body. The apparent volume of distribution in human body is 2.9 to 7L·kg -1. It is concentrated in lymphoid tissues and mainly accumulates in tissues with high fat content, such as liver and pancreas. The adrenal glands and fat are less distributed in the brain. Most cyclosporin A is oxidatively metabolized by the CYP3A4 in the liver, and a small part is metabolized by the intestinal wall and kidney. The cyclosporin A metabolites are mainly excreted through the bile, and less than 1% of the original drug is excreted from the urine and bile. The removal rate is around 0.35L·kg -1·h -1.
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