Ciclosporin

Ciclosporin (pronounced /ˌsaɪkləˈspɔrən/) , cyclosporine (USAN) or cyclosporin (former BAN), is an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the patient's immune system and so the risk of organ rejection. It has been studied in transplants of skin, heart, kidney, lung, pancreas, bone marrow and small intestine. Ciclosporin A, the main form of the drug, is a cyclic nonribosomal peptide of 11 amino acids (an undecapeptide) produced by the fungus Tolypocladium inflatum Gams, initially isolated from a Norwegian soil sample.^[1]

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Indications

The immuno-suppressive effect of cyclosporin was discovered on January 31, 1972, by employees of Sandoz (now Novartis) in Basel, Switzerland, in a screening test on immune-suppression designed and implemented by Dr.Hartmann F. Stähelin, M.D. The success of Ciclosporin A in preventing organ rejection was shown in liver transplants performed by Dr. Thomas Starzl at the University of Pittsburgh hospital. The first patient, on March 9, 1980, was a 28-year-old woman. ^[2] Ciclosporin was subsequently approved for use in 1983.

Apart from in transplant medicine, ciclosporin is also used in psoriasis, severe atopic dermatitis and infrequently in rheumatoid arthritis and related diseases, although it is only used in severe cases. It has been investigated for use in many other autoimmune disorders. Ciclosporin has also been used to help treat patients with ulcerative colitis who do not respond to treatment with steroids. ^[3] This drug is also used as a treatment of posterior or intermediate uveitis with non-infective etiology.

Ciclosporin A has been investigated as a possible neuroprotective agent in conditions such as traumatic brain injury, and has been shown in animal experiments to reduce brain damage associated with injury.^[4] Ciclosporin A blocks the formation of the mitochondrial permeability transition pore, which has been found to cause much of the damage associated with head injury and neurodegenerative diseases.

Mode of action

Ciclosporin is thought to bind to the cytosolic protein cyclophilin (immunophilin) of immunocompetent lymphocytes, especially T-lymphocytes. This complex of ciclosporin and cyclophylin inhibits calcineurin, which under normal circumstances is responsible for activating the transcription of interleukin-2. It also inhibits lymphokine production and interleukin release and therefore leads to a reduced function of effector T-cells. It does not affect cytostatic activity. It also has an effect on mitochondria. Ciclosporin A prevents the mitochondrial PT pore from opening, thus inhibiting cytochrome c release, a potent apoptotic stimulation factor. However, this is not the primary mode of action for clinical use but rather an important effect for research on apoptosis.

Adverse effects and interactions

Treatment may be associated with a number of potentially serious adverse drug reactions (ADRs) and adverse drug interactions. Ciclosporin interacts with a wide variety of other drugs and other substances including grapefruit juice, although there have been studies into the use of grapefruit juice to increase the blood level of ciclosporin.

ADRs can include gum hyperplasia, convulsions, peptic ulcers, pancreatitis, fever, vomiting, diarrhea, confusion, breathing difficulties, numbness and tingling, pruritus, high blood pressure, potassium retention and possibly hyperkalemia, kidney and liver dysfunction (nephrotoxicity & hepatotoxicity), and obviously an increased vulnerability to opportunistic fungal and viral infections.

An alternate form of the drug, ciclosporin G (OG37-324), has been found to be much less nephrotoxic than the standard ciclosporin A^[5]. Ciclosporin G (Mol. mass 1217) differs from ciclosporin A in the amino acid 2 position, where an L-nor-valine replaces the α-aminobutyric acid. ^[6]

Formulations

The drug is marketed by Novartis under the brand names Sandimmune, the original formulation, and Neoral for the newer microemulsion formulation. Generic ciclosporin preparations have been marketed under various trade names including Cicloral (Sandoz/Hexal) and Gengraf (Abbott). Since 2002 a topical emulsion of ciclosporin for treating keratoconjunctivitis sicca has been marketed under the trade name Restasis. Annual sales of ciclosporin are around $1 billion.

The drug is also available in a dog preparation manufactured by Novartis called Atopica. Atopica is indicated for the treatment of atopic dermatitis in dogs. Unlike the human form of the drug, the lower doses used in dogs mean the drug acts as an immuno-modulator and has fewer side effects than in man. The benefits of using this product include the reduced need for concurrent therapies to bring the condition under control.

References

1. ^ Borel, Jean F. (one of the original researchers), "History of the discovery of cyclosporin and of its early pharmacological development," Wien Klin Wochenschr (2002) 114/12: 433–437. Some sources list the fungus under an alternative species name Hypocladium inflatum gams such as Pritchard, DI. 2005. "Sourcing a chemical succession for cyclosporin from parasites and human pathogens". Drug Discovery Today 10 [10]: 688-691 and Walter Sneader 2005. "Ciclosporin" in: "Drug Discovery - A History", John Wiley & Sons, pages: 298-299 (refs. page 315). However, the name, Tolypocladium inflatum Gams, also appears in several other articles including in a 2001 online publication by Harriet Upton entitled "Origin of drugs in current use: the cyclosporin story" (retrieved June 19, 2005). Mark Plotkin states in his book Medicine Quest, Penguin Books 2001, pages 46-47, that in 1996 mycology researcher Kathie Hodge found that it is in fact a species of Cordyceps.
2. ^ Starzl and others (1981). "Liver transplantation with use of cyclosporin a and prednisone.". N Engl J Med 305 (5): 266-9.
3. ^ Lichtiger S, Present D, Kornbluth A, Gelernt I, Bauer J, Galler G, Michelassi F, Hanauer S (1994). "Cyclosporine in severe ulcerative colitis refractory to steroid therapy.". N Engl J Med 330 (26): 1841-5. PMID 8196726.
4. ^ Sullivan PG, Thompson M, and Scheff SW. 2000. "Continuous Infusion of Cyclosporin A Postinjury Significantly Ameliorates Cortical Damage Following Traumatic Brain Injury". Experimental Neurology. 161 [2]: 631-637.
5. ^ Henry et al. 1995. "A clinical trial of cyclosporine G in cadaveric renal transplantation". Pediatric Nephrology ix:supplement 1.
6. ^ Calne et al. 1985. "Cyclosporin G: Immunosuppressive Effect in Dogs with Renal Allografts". Lancet ii:1342.

See also

• Cremophor EL ( Additive in Sandimmune )
• Castor oil ( Additive in Sandimmune )