Cardiac disease
Ciclosporin has been used experimentally to treat cardiac hypertrophy (an increase in cell volume). Inappropriate opening of the mitochondrial permeability transition pore (MPTP) manifests in ischemia (blood flow restriction to tissue) and reperfusion injury (damage occurring after ischemia when blood flow returns to tissue), after myocardial infarction (heart attack) and when mutations in mitochondrial DNA polymerase occur. The heart attempts to compensate for disease state by increasing the intracellular Ca2+ to increase the contractility cycling rates. Constitutively high levels of mitochondrial Ca2+ cause inappropriate MPTP opening leading to a decrease in the cardiac range of function, leading to cardiac hypertrophy as an attempt to compensate for the problem.Cyclosporin A has been shown to decrease cardiac hypertrophy by affecting cardiac myocytes in many ways. Cyclosporin A binds to cyclophilin D to block the opening of MPTP, and thus decreases the release of protein cytochrome C, which can cause programmed cell death. CypD is a protein within the MPTP that acts as a gate; binding by cyclosporin A decreases the amount of inappropriate opening of MPTP, which decreases the intramitochondrial Ca2+. Decreasing intramitochondrial Ca2+ allows for reversal of cardiac hypertrophy caused in the original cardiac response. Decreasing the release of cytochrome C caused decreased cell death during injury and disease. Cyclosporin A also inhibits the phosphatase calcineurin pathway (14). Inhibition of this pathway has been shown to decrease myocardial hypertrophy. Veterinary use
The medication is approved in the United States for the treatment of atopic dermatitis in dogs.
Ciclosporin, also spelled cyclosporine and cyclosporin, is a calcineurin inhibitor, used as an immunosuppressant medication. It is a natural product. It is taken orally or  intravenously for rheumatoid arthritis, psoriasis, Crohns disease, nephrotic syndrome, and in organ transplants to prevent rejection. It is also used as eye drops for keratoconjunctivitis sicca (dry eyes).Common side effects include high blood pressure, headache, kidney problems, increased hair growth, and vomiting. Other severe side effects include an increased risk of infection, liver problems, and an increased risk of lymphoma. Blood levels of the medication should be checked to decrease the risk of side effects. Use during pregnancy may result in preterm birth; however, ciclosporin does not appear to cause birth defects.Ciclosporin is believed to work by decreasing the function of lymphocytes. It does this by forming a complex with cyclophilin to block the phosphatase activity of calcineurin, which in turn decreases the production of inflammatory cytokines by T-lymphocytes.Ciclosporin was isolated in 1971 from the fungus Tolypocladium inflatum and came into medical use in 1983. It is on the World Health Organizations List of Essential Medicines. In 2019, it was the 195th most commonly prescribed medication in the United States, with more than 2 million prescriptions that year. It is available as a generic medication. Medical uses
Ciclosporin is indicated to treat and prevent graft-versus-host disease in bone marrow transplantation and to prevent rejection of kidney, heart, and liver transplants.