Until now, glucocorticoids always play a leading role in the lupus treatment, and the lupus's prognosis has been greatly improved by the treatment of serious flare-ups with a combination of high-dose corticosteroids and immunosuppressants, notably mycophenolate mofetil (MMF) together with hydroxychloroquine (Plaquenil), survival at 10 years being 70 to 90%. However, corticosteroid treatment is also a major cause of morbidity and mortality, and with 60 years of experience, consensus about "appropriate" dosages, route of administration and tapering regimes has not been reached. In addition, there is a large variability in clinical response to corticosteroid therapy which may be attributed to heterogeneity of SLE, drugs interaction or to environmental and genetic factors, especially to polymorphism of the MDR (multi-drug resistance) -1 and NR3C1 (glucocorticoid nuclear receptor subfamily 3, group C, member 1). There are no previous studies investigating the role of MDR-1 and NR3C1 genes polymorphisms in the response to corticosteroids in lupus patients Drug monitoring of immunosuppressive drugs has been largely explored in renal transplantation and in a lesser extend in SLE (especially for mycophenolic acid). Relationship between prednisolone PK and clinical efficacy/toxicity have been also shown previously especially in renal transplant population. In patients with SLE, only two small series (8 children, 25 adults) have explored this relationship, and suggested that SLE activity and corticosteroid toxicity might be related to prednisolone AUC. Thus, limited data suggest that prednisone monitoring may optimize treatment efficacy and minimize adverse events.