Cyclosporin A-Derivative 1 Free base is primarily used in the field of immunology and transplantation medicine. It acts as an immunosuppressive agent, helping to prevent the rejection of transplanted organs by inhibiting the activity of T-cells, which play a key role in the immune response. This derivative is particularly valuable in cases where patients require a tailored immunosuppressive regimen due to variations in drug metabolism or sensitivity. In addition to transplantation, it is also explored in the treatment of autoimmune diseases such as rheumatoid arthritis and psoriasis, where it helps to modulate the overactive immune system. Research is ongoing to assess its potential in other inflammatory conditions and its efficacy compared to other immunosuppressive drugs. Its application is carefully monitored due to the risk of side effects, including nephrotoxicity and hypertension.