Cyclosporin A

This is an immunosuppressive drug that is becoming the drug of choice for transplantation. It may be of use in the management of severe autoimmune diseases.

Cyclosporin blocks cytotoxic T cell activation by:

• inhibits the formation of a calcineurin-dependent factor essential for the transcription of the interleukin-2 gene, thereby reducing production of interleukin (IL2) by activated T cells and inhibits expression of IL-2 receptors by cytotoxic T cells
• reduces the response of T helper cells to IL-1
• does not affect proliferation of suppressor T cells
• inhibits interferon production by lymphocytes

The bioavailability of cyclosporin A is dependent on the presence of bile salts which may be reduced in patients with liver transplantation. This problem however has been significantly reduced since the advent of a micro-emulsion formulation of cyclosporin whose absorption is independent of bile in the small intestine.

Patients treated with cyclosporin A should have their blood pressure and renal function monitored regularly.