Cyclosporin A is a cyclic nonribosomal peptide of eleven amino acids; an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the patient’s immune system, and therefore the risk of organ rejection. Also causes reversible inhibition of immunocompetent lymphocytes in the G0- and G1-phase of the cell cycle. It has a role as an antifungal agent, an antirheumatic drug, a dermatologic drug, an immunosuppressive agent, a metabolite, a carcinogenic agent, an anti-asthmatic drug, an EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor, an anticoronaviral agent and a geroprotector.