Immunosuppression schemes vary from institution to institution, but most involve a three-drug regimen including cyclosporine, azathioprine, and corticosteroids. Some centers additionally treat heart transplant recipients with lymphocytotoxic agents (i.e. antithymocyte globulin, antilymphocyte globulin, OKT3) to decrease the risk of rejection in the immediate postoperative period.
We use the interleukin 2 (IL-2) inhibitor tacrolimus in place of cyclosporine for primary immunosuppressive therapy in heart transplant recipients. Compared with cyclosporine (also an IL-2 inhibitor), tacrolimus-treated heart transplant recipients have a lower incidence of hypertension and an improved quality of life. However, in a series of liver transplant patients treated with either tacrolimus or cyclosporine, the tacrolimus-treated group displayed a twofold increase in neuro- and nephrotoxicity. Since toxicity and efficacy are dependent on blood levels, and given the wide array of drug interactions seen with both cyclosporine and tacrolimus, adding or withdrawing medications from the transplant patient's regimen requires caution and knowledge of drug interaction. Medications that may alter each other's blood levels are listed in Table 4 and Table 5.
Table 4 Drugs known to interact with cyclosporine and their effect on cyclosporine serum levels
Table 5 Based on clinical experience these medications may alter tacrolimus levels (no formal drug interaction studies with tacrolimus have been conducted)
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