FRI0331 Trough concentration of mycophenolic acid correlates with renal function and serum albumin level in japanese patients with sle

Background Mycophenolate mofetil (MMF) is an immunosuppressant used for treatment of lupus nephritis. MMF is converted to mycophenolic acid (MPA) by esterases, which is the active metabolite with pharmacological activities. A fixed dose of 2–3 g/day is administered as remission induction therapy.1 The usefulness of therapeutic drug monitoring (TDM) of MMF has not been elucidated. Moreover, little is known about the factor that affects the concentration of MPA in Asian patients. Objectives The aim of this study is to investigate the factor that affects the trough concentration of MPA in Japanese patients with SLE. Methods We recruited the SLE cases whose trough concentrations of MPA were measured from 2014 to 2017 at Kyoto University Hospital. When trough concentrations were measured multiple times in each patient with the same dose of MMF, median concentration was used for the analyses. Linear regression analysis was performed to identify the factor that affects the trough concentration of MPA. The association of trough concentration of MPA and adverse effects of MMF was investigated as well. Results Total of 20 cases were recruited and 43 trough concentrations were included for the analyses. The median daily dose of MMF (g) was 1.5 (range; 0.25–3.0) and the median trough concentration of MPA (μg/ml) was 2.0 (range; 0.4–15.0). Linear regression analysis (table 1) revealed that trough concentration of MPA was correlated with daily dose of MMF (p=0.0081, r=0.40, figure 1A), serum albumin level (p=3.3x10–4, r=0.52, figure 1B) and creatinine clearance (p=1.8x10–5, r=−0.60, figure 1C). Daily dose of prednisolone and serum C4 level were correlated with trough concentration of MPA as well, though multicollinearity was found in these two variables and serum albumin or creatinine clearance. Multivariate analysis (table 2) revealed that serum albumin and creatinine clearance were independently associated with trough concentration of MPA (p=6.2x10–4 and 1.6 × 10–5, respectively). Adverse effects of MMF, such as diarrhoea and cytopenia, were not associated with trough concentration of MPA. Conclusions Trough concentration of MPA was correlated with daily dose of MMF, serum albumin level and creatinine clearance. Reference [1] Ann Rheum Dis2012;71:1771–82. Disclosure of Interest None declared