Chapter 50: Immunosuppressant Drugs – Transplants & Autoimmune Therapy

The core function of the immune system is to differentiate self from non-self, employing cellular immunity mediated by T lymphocytes, which is the specific target of most immunosuppressive therapy. Transplantation carries the risk of three types of rejection—hyperacute, acute, and chronic—with immunosuppressants required indefinitely following a successful transplant. These drugs operate by selectively suppressing T-lymphocyte cell lines, resulting in a pharmacologically immunocompromised state. Major drug classes covered include calcineurin inhibitors (like cyclosporin and tacrolimus), which inhibit the synthesis of the cytokine mediator interleukin-2 (IL-2); antimetabolites (such as azathioprine and mycophenolate mofetil), which prevent T-cell proliferation; mTOR inhibitors (sirolimus); and biologics (basiliximab). Due to the narrow therapeutic index of many immunosuppressants, adverse effects are significant, including a heightened and lifelong risk for opportunistic infections and various cancers, as well as organ-specific toxicities like nephrotoxicity caused by cyclosporin and tacrolimus. Drug interactions are highly common, often involving the cytochrome P450 enzyme system, and patients must be cautioned against consuming grapefruit or grapefruit juice, as this dramatically increases drug levels, potentially leading to toxicity. Nursing care involves meticulous baseline assessment of all body systems, monitoring lab values (BUN, creatinine, WBC counts) for signs of toxicity or bone marrow suppression, educating patients on the necessity of strict adherence to complex dosing schedules, and teaching the immediate reporting of signs of infection or organ rejection (e.g., fever or decreased urine output).