Cyclosporine

Sandimmune / Neoral / Restasis

Cyclosporine (ciclosporin) is a cyclic peptide of 11 amino acids, originally isolated from a soil fungus, that became one of the most consequential drugs in modern medicine. Its arrival in the 1980s transformed organ transplantation from a risky rarity into routine therapy by giving doctors a way to suppress the immune attack on a transplanted organ (rejection) more selectively than the crude immunosuppression available before. Cyclosporine is a calcineurin inhibitor. Inside T-cells it binds a protein called cyclophilin, and the resulting complex blocks calcineurin, an enzyme that normally activates the transcription factor NFAT. By interrupting this pathway, cyclosporine suppresses production of interleukin-2 and other signals that T-cells use to multiply and mount an immune response. The effect is powerful, targeted immunosuppression that dampens rejection and autoimmune inflammation. Clinically, cyclosporine is used to prevent rejection after kidney, liver, heart, and other organ transplants, usually as part of a multi-drug regimen. It also treats autoimmune and inflammatory diseases including severe psoriasis, rheumatoid arthritis, and certain kidney conditions, and as a topical eye emulsion (Restasis and others) it treats chronic dry-eye disease driven by inflammation. Its absorption from the older oil-based formulation was erratic, so a microemulsion form (Neoral) with more reliable uptake was developed; the two are not automatically interchangeable. Cyclosporine requires careful management. It has a narrow therapeutic window and is monitored with blood levels; its main risks include kidney toxicity, high blood pressure, tremor, gum overgrowth, increased hair growth, and — because it suppresses immunity — a higher risk of infections and certain cancers over time. It interacts with many drugs and with grapefruit. Cyclosporine is a prescription medicine used under specialist supervision, not a wellness product.