Calcineurin Inhibitors (CNIs) have a significant history in the field of medicine, particularly in transplantation and immunology. The first CNI, cyclosporine, was discovered in the 1970s from a soil fungus and became a groundbreaking immunosuppressive agent after its introduction in clinical practice in the early 1980s for organ transplantation. It revolutionized transplant medicine by significantly improving graft survival rates. Following cyclosporine, tacrolimus was developed in the late 1980s, offering even more potent immunosuppressive effects. Both drugs inhibit the activity of calcineurin, an important enzyme in T-cell activation, effectively dampening the immune response. Over the years, these agents have been widely adopted for various autoimmune diseases and post-transplant management, shaping the landscape of modern immunotherapy and significantly enhancing outcomes for patients with organ transplants.
