Survey of cyclosporine therapeutic ranges, assay methodology, and use of 'sparing agents' in Australasian transplant centers.

Since its introduction in the 1980s, cyclosporine has become the major immunosuppressive drug used in organ transplantation. Despite widespread experience with this expensive agent, a number of controversial issues remain. These include the use of sparing agents to allow a lower dose of cyclosporine to be prescribed, specificity of assay method, and values quoted as therapeutic ranges. The authors surveyed organ transplant centers in Australia and New Zealand to ascertain local practices and found considerable variability in the use and dosage of sparing agents, cyclosporine assay method, and therapeutic ranges. The implications of these differences are discussed.