Tacrolimus may be superior to cyclosporine in liver transplantation and is being used in many centers. The ED physician who may encounter transplant patients should be familiar with these agents. An overview of the common immunosuppressant drugs follows. Cyclosporine achieves its effects through reversible inhibition of immunocompetent lymphocytes in the G0 and G1 phases of cell division. Cyclosporine also inhibits production and release of lymphokines, including interleukin-2.
Elimination is primarily biliary, with some excretion into the urine.
Cyclosporine is dosed according to blood levels and renal function. The dose is highly individualized because of variable absorption, elimination, and effect on renal function. The principal toxic effect of cyclosporine is nephrotoxicity, manifested acutely by elevations in BUN and creatinine. This effect usually is reversible with reductions in dosage. However, an irreversible form is associated with histologic changes in the kidney.