inflammatory response by preventing the chemotaxis and recruitment of mediating lymphocytes Relatively common acute adverse effects include hypertension, hyperglycemia (sometimes requiring insulin), psychosis, and joint pain Chronic adverse effects include the Cushing syndrome, bone demineralization, linear growth delay/arrest, adrenal suppression, and cataracts CNIs including tacrolimus and cyclosporine are currently the primary longterm immunosuppressant agents for pediatric liver transplant recipients Common side effects of tacrolimus include hyperglycemia (sometimes requiring insulin), anorexia, hypertension, headache, increased creatinine, and renal electrolyte wasting (particularly magnesium and potassium) Less common adverse effects of tacrolimus include dermatologic diseases, such as eczema, common warts (the severity of which can range from mild to disfiguring), and neurotoxicity (seizures) Many of these side effects are dose dependent Adverse effects of cyclosporine are similar to those of tacrolimus, with hypertension, renal injury, infection, skin problems, PTLD, and seizures Cyclosporine further causes cosmetic changes including hirsutism, coarsening of facial features, and gingival hyperplasia; these findings are not present with tacrolimus use Renal function is a primary concern as CNIs contribute to both acute and chronic posttransplant renal dysfunction The CNIs, as well as the purine inhibitors, enhance skin sensitivity to UV irradiation; as such, all patients on immunosuppression are cautioned to use high SPF sun screen/sun block and cover up when in the sun Mycophenolate is an ester of mycophenolic acid with lymphocytic antiproliferative properties that selectively inhibits proliferation of B and T lymphocytes by inhibiting de novo purine nucleotide synthesis Mycophenolate is used as a short-term or as maintenance adjuvant immunosuppressive therapy Common adverse effects include gastrointestinal symptoms, such as diarrhea and cramping, and marrow suppression Other effects include vomiting, anorexia, leukopenia, anemia, and infection Azathioprine can be used as an adjuvant immunosuppressive therapy in combination with a CNI and/or corticosteroid therapy Azathioprine is rapidly converted to 6-mercaptopurine, the active form of the drug, which acts as a lymphocytic antiproliferative by inhibition of purine synthesis The most common adverse effect is myelosuppression Idiosyncratic reactions include drug fever, hepatotoxicity, and pancreatitis and there is also an increased risk of infection Sirolimus is a newer immunosuppressive medication with growing indications in children Sirolimus inhibits T-lymphocyte activation and proliferation in response to antigenic and cytokine stimulation Sirolimus has been used in the pediatric transplant population as a single agent or in combination with CNIs It is